Add git push and git push --tags to RELEASING_RAILS.rdoc

RELEASING_RAILS.rdoc

@@ -96,6 +96,8 @@ what to do in case anything goes wrong:
     $ rake all:build
     $ git commit -am'updating RAILS_VERSION'
     $ git tag -m'tagging rc release' v3.0.10.rc1
+    $ git push
+    $ git push --tags
     $ for i in $(ls dist); do gem push $i; done
 
 === Send Rails release announcements