Merge branch...

Merge branch 'ld-docs-integrations-api-provide-reason-for-GitLab-for-Slack-app-create-being-disabled' into 'master' 

Give reason why Slack app creation is disabled

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/148344



Merged-by: Ashraf Khamis <akhamis@gitlab.com>
Approved-by: Ashraf Khamis <akhamis@gitlab.com>
Co-authored-by: Luke Duncalfe <lduncalfe@eml.cc>