doc: Configuring and initializing Helm Tiller

Closes #49025

See merge request gitlab-org/gitlab-ce!20515

Prefer using direct links in docs styleguide

See merge request gitlab-org/gitlab-ce!20832

Adds rack attack disabled by default notice to documentation

See merge request gitlab-org/gitlab-ce!20833

Disable Rack Attack by default

Closes #40973

See merge request gitlab-org/gitlab-ce!16669

Enable frozen string in presenters and policies

See merge request gitlab-org/gitlab-ce!20819

i18n: externalize strings from 'app/views/layouts'

See merge request gitlab-org/gitlab-ce!19766

Bump html-pipeline to 2.8.4

See merge request gitlab-org/gitlab-ce!20828

Replace snake case in SCSS variables

See merge request gitlab-org/gitlab-ce!20799

Use limit parameter to retrieve Wikis from Gitaly

See merge request gitlab-org/gitlab-ce!20764

Fix missing ` in users.md

See merge request gitlab-org/gitlab-ce!20817

Replace author_link snake case in stylesheets, specs, and helpers

Closes #30921

See merge request gitlab-org/gitlab-ce!20797

Add frozen_string_literal to migration templates

See merge request gitlab-org/gitlab-ce!20829

Update doc/ci/docker/using_docker_build.md

Closes #48691

See merge request gitlab-org/gitlab-ce!20426

Part of #47424

In 2.8.3, it was possible to modify a constant without knowing it, which
led to a major performance regression (https://gitlab.com/gitlab-org/gitlab-ce/issues/49409).
Now attempting to modify the HTML::Pipeline::SanitizationFilter.WHITELIST will result in
"can't modify frozen Hash".

See https://github.com/jch/html-pipeline/pull/299.