Docs: add details about restricted SSH keys

Closes #50489

See merge request gitlab-org/gitlab-ce!25478

Add an index page to admin area section

Closes #55234

See merge request gitlab-org/gitlab-ce!25375

Resolve "/admin/runners page fails with an SQL Statement Timeout"

Closes #53325

See merge request gitlab-org/gitlab-ce!25220

Lower the allowed Gitaly call count to 30

See merge request gitlab-org/gitlab-ce!25467

Prior to this change, 35 Gitaly RPCs were allowed. But recently there's
been a renewed interest in performance. By lowering the number of
calls new N + 1's will pop up.

Later commits will add blocks to ignore the raised errors, followed by
an issue for each to be fixed.

Ensure all lists are surrounded by new lines

See merge request gitlab-org/gitlab-ce!25479

Markdown renderers find it easier to determine
where lists start and end when lists are surrounded
by new lines.

For consistency, also ensure entries in the list
are aligned when they span multipls lines.

Improve snippets empty state

Closes #44045 and #20847

See merge request gitlab-org/gitlab-ce!18348

Only show borders around markdown images in notes

Closes #55703

See merge request gitlab-org/gitlab-ce!25448

Resolve "Fix danger commit messages check"

Closes #58057

See merge request gitlab-org/gitlab-ce!25489

Update dependency @gitlab/svgs to ^1.54.0

See merge request gitlab-org/gitlab-ce!25488

Port EE System Header And Footer feature to CE

Closes #55057

See merge request gitlab-org/gitlab-ce!25241

Resolve "Units are appended to Y axis label on metrics dashboard"

Closes #56477

See merge request gitlab-org/gitlab-ce!25485

Remove duplicate units from metrics dashboard graphs

Move gfm_auto_complete_spec.js to Jest

See merge request gitlab-org/gitlab-ce!25463

Linked no EFS article to backup section

See merge request gitlab-org/gitlab-ce!25302

Resolve "Only load syntax highlighting css when selected"

Closes #57739 and #56873

See merge request gitlab-org/gitlab-ce!25232

Bump version_sorter to version 2.2.4

See merge request gitlab-org/gitlab-ce!25487

Merge branch '52198-timer-is-vertically-misaligned-for-delayed-jobs-in-pipeline-actions' into 'master'

fix-52198-timer-is-vertically-misaligned-for-delayed-jobs-in-pipelactions

Closes #52198

See merge request gitlab-org/gitlab-ce!25117

Fix select2 import for project import app namespace select

See merge request gitlab-org/gitlab-ce!25307

Setup Jest for EE (CE backport)

See merge request gitlab-org/gitlab-ce!25468

Allow users to compare branches on a read-only instance

See merge request gitlab-org/gitlab-ce!25414

Signed-off-by: NDmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Add "How to seed a database with millions of rows" section

See merge request gitlab-org/gitlab-ce!25439

[ci skip]

Compatible with https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5162

Docs: Fix all anchors related to YAML

See merge request gitlab-org/gitlab-ce!25459