Follow-up from "Update capitalization and backticks in /doc/dev"

The following discussions from !17199 (merged) should be addressed:

• @eread started a discussion:

  We could consider standardizing on "Markdown" (capital M).

• @eread started a discussion:

  We should use https for these, either way.

  - [Site architecture](site_architecture/index.md) - How <https://docs.gitlab.com> is built.

• @eread started a discussion:

  11.4 onwards, but available on <https://docs.gitlab.com/> on the same day it was merged.

  Things aren't moved to archives the same day they are merged.

• @eread started a discussion:

  The [GitLab Docs site](https://docs.gitlab.com) supports embedded videos.

  Elsewhere you used uppercase D for Docs.

• @eread started a discussion:

  Alert boxes only render on the GitLab Docs site (<http://docs.gitlab.com>).

  Subtle difference. "Properly" implies that outside the docs, it's broken. We mean it either renders, or it doesn't, rather than it "renders properly" vs "renders improperly".

• @eread started a discussion:

  the [Elasticsearch integration documentation](../integration/elasticsearch.md#enabling-elasticsearch).

  Needs a period, though.

• @eread started a discussion:

  GitLab provides `Tracking`, an interface that wraps the [Snowplow JavaScript Tracker](https://github.com/snowplow/snowplow/wiki/javascript-tracker) for tracking custom events. There are a few ways to utilize tracking, but each generally requires at minimum, a `category` and an `action`. Additional data can be provided that adheres to our [Feature instrumentation taxonomy](https://about.gitlab.com/handbook/product/feature-instrumentation/#taxonomy).

  While we're here.

• @eread started a discussion:

  ### Enabling feature for preproduction testing

  "internal" is a bit vague.

• @eread started a discussion:

  It describes how to set up Gitaly, the various components of Gitaly and what they do, and how to run its test suites.

  While we're here.

changed milestone to %12.4

added Technical Writing documentation labels

This one also needs https: Alert boxes only render on the GitLab Docs site (<http://docs.gitlab.com>).

marked the checklist item @eread started a discussion: as completed

marked the checklist item @eread started a discussion: as completed

marked the checklist item @eread started a discussion: as completed

marked the checklist item @eread started a discussion: as completed

marked the checklist item @eread started a discussion: as completed

marked the checklist item @eread started a discussion: as completed

marked the checklist item @eread started a discussion: as completed

marked the checklist item @eread started a discussion: as completed

mentioned in merge request !18430 (merged)

added docsimprovement label

closed via merge request !18430 (merged)

mentioned in commit a932ec3e