Merge branch 'Docs-Repo-Size' into 'master'

Update index.md to add link to reducing repo size doc

See merge request gitlab-org/gitlab-ce!20281

doc/user/gitlab_com/index.md

@@ -64,7 +64,8 @@ Below are the current settings regarding [GitLab CI/CD](../../ci/README.md).
 
 ## Repository size limit
 
-The maximum size your Git repository is allowed to be including LFS.
+The maximum size your Git repository is allowed to be, including LFS. If you are near
+or over the size limit, you can [reduce your repository size with Git](../project/repository/reducing_the_repo_size_using_git.md).
 
 | Setting                 | GitLab.com        | Default       |
 | -----------             | ----------------- | ------------- |