pygrass docs: add link to table of parser standard options

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@66723 15284696-431f-4ddb-bdfa-cd5b030d7da7

lib/python/script/core.py

@@ -706,6 +706,9 @@ def parser():
     dictionaries containing option/flag values, keyed by lower-case
     option/flag names. The values in "options" are strings, those in
     "flags" are Python booleans.
+
+    Overview table of parser standard options:
+    https://grass.osgeo.org/grass71/manuals/parser_standard_options.html
     """
     if not os.getenv("GISBASE"):
         print("You must be in GRASS GIS to run this program.", file=sys.stderr)