Move lfs user doc to git topics directory

What does this MR do?

Moves a few docs to /topics/git/lfs as requested.

Source	Destination
administration/git_annex.md	Unchanged, mostly admin docs
administration/lfs/lfs_administration.md	Unchanged, for now
administration/lfs/manage_large_binaries_with_git_lfs.md	topics/git/lfs/index.md
administration/lfs/migrate_from_git_annex_to_git_lfs.md	topics/git/lfs/migrate_from_git_annex_to_git_lfs.md
topics/git/migrate_to_git_lfs/index.md	topics/git/lfs/migrate_to_git_lfs.md

Related issues

Closes #210354 (closed)

Moving docs to a new location?

Read the guidelines: https://docs.gitlab.com/ee/development/documentation/index.html#changing-document-location

• Make sure the old link is not removed and has its contents replaced with a link to the new location.
• Make sure internal links pointing to the document in question are not broken.
• Search and replace any links referring to old docs in GitLab Rails app, specifically under the app/views/ and ee/app/views (for GitLab EE) directories.
• Make sure to add redirect_from to the new document if there are any Disqus comments on the old document thread.
• Update the link in features.yml (if applicable) -> gitlab-com/www-gitlab-com#6841 (closed)
• If working on CE and the ee-compat-check jobs fails, submit an MR to EE with the changes as well (https://docs.gitlab.com/ce/development/documentation/index.html#cherry-picking-from-ce-to-ee).
• Ping one of the technical writers for review.