Describe the supported version of group-level variables API in document

What does this MR do?

This MR fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/36543#note_37876984

Are there points in the code the reviewer needs to double check?

Why was this MR needed?

We should mention this earlier. This MR catches it up.

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• [-] Changelog entry added, if necessary
• Documentation created/updated
• [-] API support added
• [-] Tests added for this feature/bug
• Review
  • [-] Has been reviewed by UX
  • [-] Has been reviewed by Frontend
  • [-] Has been reviewed by Backend
  • [-] Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together

What are the relevant issue numbers?

https://gitlab.com/gitlab-org/gitlab-ce/issues/36543#note_37876984

Close https://gitlab.com/gitlab-org/gitlab-ce/issues/36543

marked the checklist item Documentation created/updated as completed

marked the checklist item Conform by the merge request performance guides as completed

marked the checklist item Conform by the style guides as completed

marked the checklist item Squashed related commits together as completed

Should we update the API documentation to confirm that these endpoints were only added in v9.5?

@markglenfletcher I agree with you!

@axil Could you review/merge this MR? The context is https://gitlab.com/gitlab-org/gitlab-ce/issues/36543#note_37876984.

assigned to @axil

changed the description

added 1 commit

• 0d433aa0 - Update group_level_variables.md

Compare with previous version

changed milestone to %9.5

approved this merge request

Should be in %9.5, thanks!

merged

@axil Thanks!

mentioned in commit 2e39826b

Picked into https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/13672, will merge into 9-5-stable ready for 9.5 RC6

mentioned in commit d047b125