Moved projection list to using chapter and created a list of transformations. Both are grouped in a section called operations.

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diff --git a/docs/source/usage/operations/transformations/hgridshift.rst b/docs/source/usage/operations/transformations/hgridshift.rst
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+.. _hgridshift:
+
+================================================================================
+Horizontal grid shift
+================================================================================
+
+Change of horizontal datum by grid shift.
+
++--------------+--------------------------------------------------------------------+
+| **Options**                                                                       |
++--------------+--------------------------------------------------------------------+
+| `+grids`     | Comma-separated list of grids to load.                             |
++--------------+--------------------------------------------------------------------+
+
+The horizontal grid shift is done by offsetting the planar input coordinates by
+a specific amount determined by the loaded grids. The simplest use case of the
+horizontal grid shift is applying a single grid::
+
+    +hgridshift +grids=nzgr2kgrid0005.gsb
+
+
+More than one grid can be loaded at the same time, for instance in case the
+dataset needs to be transformed spans several countries. In this example grids
+of the continental US, Alaska and Canada is loaded at the same time::
+
+    +hgridshift +grids=@conus,@alaska,@ntv2_0.gsb,@ntv_can.dat
+
+The ``@`` in the above example states that the grid is optional, in case the grid
+is not found in the PROJ.4 search path. The list of grids is prioritized so that
+grids in the start of the list takes presedence over the grids in the back of the
+list.
+