Improve the documentation for TemplateHook.

Review Request #9629 - Created Feb. 12, 2018 and submitted

Christian Hammond
Review Board

This fleshes out some of the TemplateHook docs, going into more detail
on a few hook points, along with linking to other extension pages that
are relevant for them. It also moves from a table-based display of names
to a definition-based display, which helps keep longer descriptions

The example has been updated to make use of alternate template hook
points, in order to avoid recommending its usage for custom CSS or
JavaScript (which static media bundles are a better solution for).

This is in preparation for some new updates to the list of available
template hook points that will be coming soon.

Built the docs and looked through them, checking for formatting and
linking errors.

David Trowbridge
  1. Ship It!
Christian Hammond
Review request changed

Status: Closed (submitted)

Change Summary:

Pushed to release-3.0.x (fc499b8)