Fix indentation in user, tutorials and install dirs

This matches lib/system_check/app/redis_version_check.rb to avoid
confusion.

Also edit rest of section

Co-authored-by: Evan Read <eread@gitlab.com>

Introduce recommended memory size of 16GB

We've had a number of customers upgrade operating systems on
PostgreSQL using replication and failover not realizing they needed
to be careful about ICU collations. This commit documents
the need to check for glibc version changes and what to do about it.

Relates to https://gitlab.com/groups/gitlab-org/-/epics/8573

Changelog: added

Prepare for the split

Related to: https://gitlab.com/gitlab-org/gitlab/-/issues/439130

Related to: https://gitlab.com/gitlab-org/gitlab/-/issues/439130

- /doc/install/requirements.md
- /doc/administration/redis/replication_and_failover_external.md
- /doc/administration/reference_architectures/2k_users.md
- /doc/administration/reference_architectures/3k_users.md
- /doc/administration/reference_architectures/5k_users.md
- /doc/administration/reference_architectures/10k_users.md
- /doc/administration/reference_architectures/25k_users.md
- /doc/administration/reference_architectures/50k_users.md

Redis 6.0 has
reached end-of-life (https://github.com/sidekiq/sidekiq/issues/5594).

The vendored Sidekiq 7 gem has backward compatibility with Redis 6.0 but
we retain 6.2.14 as the RECOMMENDED_REDIS_VERSION.

Changelog: changed

Makes use of markdownlint for automated cleanup

Because for now, we're changing the format.

Related to: https://gitlab.com/gitlab-org/gitlab-docs/-/issues/1751

Fix indentation of lists and table alignment

Update the links in all docs except user and admin pages

Contributes to https://gitlab.com/gitlab-org/gitlab/-/issues/421591

Follow-up for
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/132111

* Remove `Gitlab::RuggedInstrumentation`
* Remove `Peek::Views::Rugged`
* Remove lint-rugged script
* Adjust tests and documentation

Changelog: removed

The cloud_connector team is not actively working on reducing memory
requirements. Sentence is being removed to reflect the reality.

Contributes to https://gitlab.com/gitlab-org/gitlab/-/issues/421591

Rugged patches were disabled in 16.5:
https://gitlab.com/gitlab-org/gitlab/-/issues/425260.

It's time to update the documentation to reflect the current state.

updating installation requirements to the suggested 12 GB of storage available and 1GB of vulnerability data

Updates from review

Also refactor upgrade paths section.