docs(gitaly): document how to move repo out of read-only
What
Add documentation on how to check if a repository is in read-only mode, and how to make it writeable.
Why
Moving the storage server of a repository can fail, and if there is a bug it could leave the repository in read-only mode, and we don't have a documented way to fix it.
Signed-off-by: Steve Xuereb sxuereb@gitlab.com