grassdocs.css: remove out-dated note (cosmetics)

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@55336 15284696-431f-4ddb-bdfa-cd5b030d7da7

man/grassdocs.css

@@ -1,5 +1,4 @@
 /* GRASS documentation site style sheet
- * (copied by 'tools/build_html_index.sh')
  *
  * send improvements to GRASS Developers list
  *