Add projection and region to grdview docstring (GenericMappingTools#1295

)

Co-authored-by: Wei Ji <23487320+weiji14@users.noreply.github.com>

pygmt/src/grdview.py

@@ -58,6 +58,13 @@ def grdview(self, grid, **kwargs):
     grid : str or xarray.DataArray
         The file name of the input relief grid or the grid loaded as a
         DataArray.
+    region : str or list
+        *xmin/xmax/ymin/ymax*\ [**+r**][**+u**\ *unit*].
+        Specify the :doc:`region </tutorials/regions>` of interest. When used
+        with ``perspective``, optionally append */zmin/zmax* to indicate the
+        range to use for the 3-D axes [Default is the region in the input
+        grid].
+    {J}
     zscale/zsize : float or str
         Set z-axis scaling or z-axis size.
     {B}