Doxygen improvements for sorc/grid_tools.fd/regional_esg_grid.fd/pmat…

…5.f90 (#372)

* part of Doxygen updates for sorc/grid_tools.fd #366
doxygen update for pmat5.f90

* part of Doxygen updates for sorc/grid_tools.fd #366
modify doxygen for grid_tools.fd/regional_esg_grid.fd/pmat5.f90

* part of Doxygen updates for sorc/grid_tools.fd #366
doxygen update for pmat5.f90

* Doxygen improvements for sorc/grid_tools.fd/regional_esg_grid.fd/pmat5.f90
Part of #366

* Doxygen improvements for sorc/grid_tools.fd/regional_esg_grid.fd/pmat5.f90
Part of #366

* doxygen fixes, clearing off doxygen warnings

* doxygen fixes, clearing off doxygen warnings

Co-authored-by: Edward Hartnett <Edward.Hartnett@noaa.gov>
Co-authored-by: Edward Hartnett <38856240+edwardhartnett@users.noreply.github.com>