docs(actions): Migrated actions section from old Getting Started docs and cleaned up related sections.

Refs #6812.
docs(events): Updated event list and cleaned up existing event docs.

Refs #6812.
docs(hook): Updated hooks docs.

Refs #6812
docs(all): Added getting started for developers.

Refs #6812
docs(all): Cleanup docs.

Refs #6812.
docs(admin): Migrated Getting Started guide from wiki.

Refs #6812.
docs(faqs): Started migrating some FAQs.
chore(cleanup): removed unused $CONFIG->installer_running variable 

fixes #4973
fix(uservalidationbyemail): makes emailsent page public

Marks uservalidationbyemail/emailsent as a public page in walled garden to
ensure that newly registered users receive a understandabe comfirmation page.

Fixes #7334
Merge pull request #7358 from stianlik/uservalidationbyemail

fix(uservalidationbyemail): makes emailsent page public
Merge pull request #7240 from brettp/docs_getting_started

Docs getting started
fix(access): always display readable access level for ACCESS_* constants

Labels for global ACCESS_* constants should always be meaningful,
and not Limited. Most obvious example is when write access arrays
are not populated with ACCESS_PUBLIC in a walled garden mode.
Or else when certain global access levels are filtered by hooks
for a select group of users

Fixes #6801
chore(docs): update the docblock for get_readable_access_level()

Cleans up the warning and provides a more detailed explaination of what the function does
Merge pull request #7353 from jdalsem/remove-unused-installer-running

chore(cleanup): removed unused $CONFIG->installer_running variable
chore(docs): renamed plugin txt files to md

fixes #3507
chore(docs): cleanup markdown text of readme files
fix(css): markdown code blocks should not should nested borders
chore(cleanup): removed unused javascript file counter.js in thewire

fixes #6933
fix(menus): allow max depth of 20 to prevent losing menu items

fixes #5570
fix(login): also allow login by email in maintenance mode

fixes #6878