init: use the two dash option in after-error suggestion

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@73262 15284696-431f-4ddb-bdfa-cd5b030d7da7

lib/init/grass.py

@@ -2065,8 +2065,8 @@ def main():
         if grass_gui == 'text' and not params.mapset:
             fatal(_("Unable to start GRASS GIS. You have the choice to:\n"
                     " - Launch the graphical user interface with"
-                    " the '-gui' switch\n"
-                    "     {cmd_name} -gui\n"
+                    " the '--gui' switch\n"
+                    "     {cmd_name} --gui\n"
                     " - Launch with path to "
                     "the location/mapset as an argument\n"
                     "     {cmd_name} /path/to/location/mapset`\n"