[ci-skip] Correct gitlab-shell installation instructions in docs
requested to merge 22352-cannot-install-gitlab-shell-on-ubuntu-server-with-no-previous-gitlab-install into master
What does this MR do?
Correct gitlab-shell installation instructions in docs
Why was this MR needed?
With the introduction of repository storages validations it becomes necessary to add the flag SKIP_STORAGE_VALIDATION to the gitlab-shell install command, since that command will create the storage paths
What are the relevant issue numbers?
Closes #22352 (closed)