Include documentation on withArray parameter when creating Cache Service

Update extensions documentation info.

Due to changes to the docs publisher system updates to the documentation are neccessary.

Add note regarding element inheritence

Add link to more info about the Civi:: facade

Certain elements are inherited from the parent 'path' if not defined. This is done in \CRM_Core_Menu::fillMenuValues.

civibuild.md - Add more D8 build-type info. Reorganize for readability.

Add clarification of what forward-compatibility means

the part about `the installation` is adding new confusion

Fix small typos

Added "see also" to gitlab wiki page

Since @mlutfy created the wiki page, it seems this might be helpful to get more eyeballs on it.

Corrected URL for Extension Review Request

Corrected URL for "unassigned review requests"

Added lab.c.o as valid repo host

Under 'Criteria for passing a review'

This URL changed today as we moved these issues to their own gitlab project.

This URL changed today as we track these requests in their own gitlab project.

Fix filename of doc to match hook name

Add Docs on new theme hooks

add text re curl installation to Ubuntu

removed a reference to an Issue with installation

Fix #616 document hook_civicrm_getAssetUrl

removed a reference to an Issue with installation on Mac OS, which is now Closed - https://github.com/michaelmcandrew/civicrm-buildkit-docker/issues/15

Replaced jira references with gitlab references

Testing: Update PHPUnit versions

Adding theming information