clarify period when the option were renamed (backport https://trac.osgeo.org/grass/changeset/64069 and https://trac.osgeo.org/grass/changeset/64058)

git-svn-id: https://svn.osgeo.org/grass/grass/branches/releasebranch_7_0@64070 15284696-431f-4ddb-bdfa-cd5b030d7da7

lib/gis/renamed_options

@@ -1,5 +1,5 @@
-### Renamed options in GRASS 7.0
-################################
+### Renamed options between GRASS GIS 6.4 and 7.0
+#################################################
 # Entries in alphabetical order
 ################################
 ### Global