[Docs] Minor changes regarding datumgrid pages (#1751) (#1760)

Update README, install.rst and resource_files.rst

3 files changed, 34 insertions, 24 deletions

diff --git a/README.md b/README.md
index 32ba08ca..d1af9dbb 100644
--- a/README.md
+++ b/README.md
@@ -23,18 +23,21 @@ See the NEWS file for changes between versions.
 
 The following command line utilities are included in the PROJ package:
 
-- proj, for cartographic projection of geodetic coordinates
-- cs2cs, for transformation from one CRS to another CRS.
-- geod, for geodesic (great circle) computations.
-- cct, for generic Coordinate Conversions and Transformations.
-- gie, the Geospatial Integrity Investigation Environment.
-- projinfo, for geodetic object and coordinate operation queries
+- `proj`: for cartographic projection of geodetic coordinates
+- `cs2cs`: for transformation from one CRS to another CRS.
+- `geod`: for geodesic (great circle) computations.
+- `cct`: for generic Coordinate Conversions and Transformations.
+- `gie`: the Geospatial Integrity Investigation Environment.
+- `projinfo`: for geodetic object and coordinate operation queries
+
+> More information on the utilities can be found on the [PROJ website](https://proj.org/apps).
 
 ## Installation
 ### Build dependencies
 
 PROJ requires C and C++11 compilers.
-It also requires SQLite3 (headers, library and executable).
+It also requires SQLite3 (headers, library and executable).  The minimum 
+version of SQLite3 required is 3.11
 
 ### Building with CMake
 
@@ -105,14 +108,14 @@ which will generate a configure script that can be used as described above.
 ### Distribution files and format
 
 Sources are distributed in one or more files.  The principle elements
-of the system are in a compress tar file named `proj-x.y.z.tar.gz` where
-"x" will indicate major release number, "y" indicates minor release
-number and "z" indicates the patch number of the release.
+of the system are stored in a compressed tar file named `proj-x.y.z.tar.gz` where
+"x" will indicate the major release number, "y" indicates the minor release
+number, and "z" indicates the patch number of the release.
 
 In addition to the PROJ software package, distributions of datum
 conversion grid files and PROJ parameter files are also available.
 The grid package is distributed under the name `proj-datumgrid-x.y.zip`,
-where "x" is the major release version and "y" the minor release
+where "x" is the major release version and "y" is the minor release
 version numbers. Similarly regional packages are distributed. The
 regional packages contain resources that are not essential to the
 functionality of PROJ but still of value to users in the region
@@ -120,7 +123,7 @@ specific to the package. All grids that were in proj-datumgrids-1.6
 remain in proj-datumgrids-1.7; the regional datumgrid files contain
 grids for datums not previously supported (prior to PROJ 5.0.0).
 
-The resource packages can be downloaded from the PROJ.4 website.
+The resource packages can be downloaded from the [PROJ website](https://proj.org/download.html).
 
 More info on the contents of the various resource packages can be
 found at the
diff --git a/docs/source/install.rst b/docs/source/install.rst
index 08edba8d..1a055b4c 100644
--- a/docs/source/install.rst
+++ b/docs/source/install.rst
@@ -34,6 +34,9 @@ the `proj-datumgrid-europe` package::
 Available is also the ``proj-datumgrid-north-america``, ``proj-datumgrid-oceania``
 and ``proj-datumgrid-world``.
 
+.. tip::
+   Read more about the various datumgrid packages available :ref:`here<datumgrid>`.
+
 Docker
 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 
@@ -123,7 +126,7 @@ PROJ is also available from the MacPorts system::
 Compilation and installation from source code
 ################################################################################
 
-The classical way of installing PROJ is via the source code distribution. The
+The classic way of installing PROJ is via the source code distribution. The
 most recent version is available from the :ref:`download page<current_release>`.
 
 You will need that and at least the standard *proj-datumgrid* package for a
diff --git a/docs/source/resource_files.rst b/docs/source/resource_files.rst
index d40f683a..40eb9731 100644
--- a/docs/source/resource_files.rst
+++ b/docs/source/resource_files.rst
@@ -6,11 +6,11 @@ Resource files
 
 A number of files containing preconfigured transformations and default parameters
 for certain projections are bundled with the PROJ distribution. Init files
-contains preconfigured proj-strings for various coordinate reference systems
-and the defaults file contains default values for parameters of select
+contain preconfigured proj-strings for various coordinate reference systems
+and the `defaults` file contains default values for parameters of select
 projections.
 
-In addition to the bundled init-files the PROJ.4 project also distribute a number
+In addition to the bundled init-files the PROJ project also distributes a number
 of packages containing transformation grids and additional init-files not included
 in the main PROJ package.
 
@@ -33,6 +33,8 @@ the GTX file format for vertical corrections. Details about the formats can be
 found in the `GDAL documentation <http://gdal.org/>`_. GDAL reads and writes
 all formats. Using GDAL for construction of new grids is recommended.
 
+.. _datumgrid:
+
 External resources and packaged grids
 -------------------------------------------------------------------------------
 
@@ -71,7 +73,8 @@ we will create new regional packages.
 Click the links to jump to the relevant README files for each package. Details
 on the content of the packages maintained there.
 
-Links to the resource packages can be found in the :ref:`download section <download>`.
+.. tip::
+   To download the various datumgrid packages head to the :ref:`download section <download>`.
 
 World package
 +++++++++++++
@@ -83,7 +86,7 @@ includes grids that have global extent, e.g. the global geoid model EGM08.
 ++++++++++++++++
 
 All packages above come in different versions, e.g proj-datumgrid-1.8 or
-proj-datumgrid-europe-1.4. The -latest packages are symbolic links to the
+proj-datumgrid-europe-1.4. The `-latest` packages are symbolic links to the
 latest version of a given packages. That means that the link
 https://download.osgeo.org/proj/proj-datumgrid-north-america-latest.zip is
 equivalent to https://download.osgeo.org/proj/proj-datumgrid-north-america-1.2.zip
@@ -94,13 +97,13 @@ equivalent to https://download.osgeo.org/proj/proj-datumgrid-north-america-1.2.z
 Other transformation grids
 -------------------------------------------------------------------------------
 
-Below is a given a list of grid resources for various countries which are not
+Below is a list of grid resources for various countries which are not
 included in the grid distributions mentioned above.
 
 Free grids
 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 
-Below is a list of grids distributed under a free and open license.
+The following is a list of grids distributed under a free and open license.
 
 Hungary
 ................................................................................
@@ -151,7 +154,7 @@ Spain
 HTDP
 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 
-This page documents use of the `crs2crs2grid.py` script and the HTDP
+This section describes the use of the `crs2crs2grid.py` script and the HTDP
 (Horizontal Time Dependent Positioning) grid shift modelling program from
 NGS/NOAA to produce PROJ compatible grid shift files for fine grade
 conversions between various NAD83 epochs and WGS84.  Traditionally PROJ has
@@ -187,7 +190,8 @@ Getting crs2crs2grid.py
 The `crs2crs2grid.py` script can be found at
 https://github.com/OSGeo/gdal/tree/trunk/gdal/swig/python/samples/crs2crs2grid.py
 
-It depends on having the GDAL Python bindings operational.  If they are not
+The script depends on having the GDAL Python bindings operational; if they are not you
+will get an error such as:
 
 
 ::
@@ -286,7 +290,7 @@ Init files
 Init files are used for preconfiguring proj-strings for often used
 transformations, such as those found in the EPSG database. Most init files contain
 transformations from a given coordinate reference system to WGS84. This makes
-it easy to transformations between any two coordinate reference systems with
+it easy to transform between any two coordinate reference systems with
 ``cs2cs``. Init files can however contain any proj-string and don't necessarily
 have to follow the *cs2cs* paradigm where WGS84 is used as a pivot datum. The
 ITRF init file is a good example of that.
@@ -295,7 +299,7 @@ A number of init files come pre-bundled with PROJ but it is also possible to
 add your own custom init files. PROJ looks for the init files in the directory
 listed in the ``PROJ_LIB`` environment variable.
 
-The format of init files made up of a identifier in angled brackets and a
+The format of init files is an identifier in angled brackets and a
 proj-string:
 
 ::