Updating redirected links in the development, install, policy
raketasks and university dirs. Should now link to final
URL to avoid redirect hops

Also fixes instances in Markdown that broke the rule.

Fixing square brackets, links, etc in:
  merge_requests.md
  vulnerabilities.md
  issues.md
  issues_statistics.md
  pipelines.md
  services.md
  group_milestones.md
  milestones.md
  runners.md
  changelog.md
  issue_workflow.md
  elasticsearch.md
  api_graphql_styleguide.md
  automatic_ce_ee_merge.md
  file_storage.md
  architecture.md
  database_debugging.md
  index.md
  index.md
  frontend_testing.md
  pry_debugging.md
  vue.md
  development_process.md

Linting rule not enabled for now
because tooling produces false
positives.

Add links to useful browser extensions and learning resources to the
FE-accessibility documentation.

This copy button manages a local instance of the Clipboard plugin
specific to it, which means it is created/destroyed on the
creation/destruction of the component. This allows it to work well in
gitlab-ui modals, as the event listeners are bound on creation of the
button.

It also allows for bindings to the `container` option of the Clipboard
plugin, which allows it to work within the focus trap set by bootstrap's
modals.

Two nitpick improvements to the following:

* set `state.isAddingUser = false` when request resulted in an error,
  as it has finished after all
* be very explicit about vuex store being a local module to avoid confusion
  about a dependency named `store`

This brings the mutation type name closer to the associated action,
so the documented example is more consistent.

We have a range of shades for most of the theme colors
Grouped them into color maps the same way Bootstrap does
for $grays already
Also add type scale utils

Start moving back to regular fe_docs
Remove Initiatives, add section to index in fe_guide
Delete some no-longer-relevant parts from principles
Update title - Progressive Enchancement is a browser-support term
and could be confused
"When to use" parts are discussed elswhere
Vue & jQuery issue is no longer relevant
Delete duplicate Security docs
Remove empty files, move event_tracking
Shuffle index sections around
Remove sections on Vue & Webpack (we say same thing in prev paragraph)
Remove link to Droplab docs

Signed-off-by: NTakuya Noguchi <takninnovationresearch@gmail.com>

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.

For the sake of consistency, removes any extraneous
consecutive blank lines from the doc suite.

- Add link to Event tracking in FE guides

- Also makes other minor Markdown fixes that were near the main fixes.

Signed-off-by: NTakuya Noguchi <takninnovationresearch@gmail.com>