Merge branch 'improve-oauth2-docs' into 'master'

Update/Improve OAuth2 Client documentation

## What does this MR do?
Improves the OAuth2 client documentation to include security hints to help people create secure clients.

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

## Why was this MR needed?
I noticed the docs didn't mention some important points and steps, this cleans that up.

## What are the relevant issue numbers?

## Screenshots (if relevant)

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [x] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support added
- Tests
  - [ ] Added for this feature/bug
  - [ ] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5665

1 files changed, 1 insertions, 0 deletions

diff --git a/CHANGELOG b/CHANGELOG
index a978ae90dac..3b567d9ec2c 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -71,6 +71,7 @@ v 8.11.0 (unreleased)
   - Add GitLab Workhorse version to admin dashboard (Katarzyna Kobierska Ula Budziszewska)
   - Allow branch names ending with .json for graph and network page !5579 (winniehell)
   - Add the `sprockets-es6` gem
+  - Improve OAuth2 client documentation (muteor)
   - Multiple trigger variables show in separate lines (Katarzyna Kobierska Ula Budziszewska)
   - Profile requests when a header is passed
   - Avoid calculation of line_code and position for _line partial when showing diff notes on discussion tab.