Merge branch 'docs-rmusoyev-add-applications-setting' into 'master'

Added User OAuth applications section

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/166494



Merged-by: Brendan Lynch <blynch@gitlab.com>
Reviewed-by: Rakhman Musoyev <rmusoyev@gitlab.com>
Reviewed-by: Brendan Lynch <blynch@gitlab.com>
Co-authored-by: Rakhman Musoyev <rmusoyev@gitlab.com>