Update groups API documentation

Closes #38922

See merge request gitlab-org/gitlab-ce!15024

Fix the writing of invalid environment refs

Closes #39182

See merge request gitlab-org/gitlab-ce!14993

Resolve "Pages API"

Closes #23000

See merge request gitlab-org/gitlab-ce!13917

Circuitbreaker backoff and retries

Closes #37383 and #38231

See merge request gitlab-org/gitlab-ce!14933

Add new files & directories in the multi-file editor

Closes #38614

See merge request gitlab-org/gitlab-ce!14839

Hides pipeline duration in commit box when it is zero (nil)

Closes #32788

See merge request gitlab-org/gitlab-ce!14979

Clean up `new-sidebar`

See merge request gitlab-org/gitlab-ce!14978

Fix code review discussion action buttons

Closes #38891

See merge request gitlab-org/gitlab-ce!14801

Fix performance of sticky.js

Closes #39332

See merge request gitlab-org/gitlab-ce!14976

Remove Sherlock usage from the performance bar

Closes #39351

See merge request gitlab-org/gitlab-ce!15000

Changing the smallest of typos

See merge request gitlab-org/gitlab-ce!15022

Use the new buttons for creating groups and projects in QA tests

Closes #39349

See merge request gitlab-org/gitlab-ce!14997

Make pipelines table in MR view usable

See merge request gitlab-org/gitlab-ce!14941

Fix CSS in load more participants

Closes #39299

See merge request gitlab-org/gitlab-ce!15005

Refactor `have_http_status` into `have_gitlab_http_status` in the specs

Closes #35644

See merge request gitlab-org/gitlab-ce!14958

Simple docs fixes

See merge request gitlab-org/gitlab-ce!15001

Removes group_avatar & group_label_subscription from global namespace

See merge request gitlab-org/gitlab-ce!15006

Fix a small typo in the delete merged branches documentation

See merge request gitlab-org/gitlab-ce!15003

Fix the description of the new branch created by an issue's new branch button

See merge request gitlab-org/gitlab-ce!15004

Moves vue resource docs into a new file & add documentation to handle 204

Closes #39369

See merge request gitlab-org/gitlab-ce!15002

Backport EE changes to group routes

Closes gitlab-ee#3794

See merge request gitlab-org/gitlab-ce!14973

Only cache the push event for the fork-source when it exists

Closes #39352

See merge request gitlab-org/gitlab-ce!14989

Adds docs regarding handling 204 response

Sherlock::Query generates a backtrace on every call to "new", which is
very slow. Formatter queries are also not displayed properly due to the
lack of "white-space: pre" in the CSS. We took a look at fixing this,
but the produced output is not really better than just displaying
queries on one line.

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/39351

Fix escaped text replacement

Closes #37724

See merge request gitlab-org/gitlab-ce!14193

removed an ID from the CSS