Strict markdown standards for internal hyperlink URLs

Fixed misnamed hook

Run the following command to do so:
./bin/hook-summary.py

Updated Joomla-specific notes.

Updated to reflect that a fix has been merged. Moved warning to the top where it is more likely to be useful. Also, seems more appropriate as a "note" than a "convention" or "tip."

Fixed funky formatting

Remove scary warning

Removed scary warning that only applies to a single point release.

WIP: Add testing documentation

Two recent SE questions have made me think that readers are missing this
key set of installing CiviCRM with civibuild (instead of with the normal
installation steps). I've added clarification here which I hope will
prevent future users from stumbling on this step.

ref:

https://civicrm.stackexchange.com/questions/19294/how-to-create-entity-in-civicrm
https://civicrm.stackexchange.com/questions/19194/unable-to-locate-folder-xml-under-the-civicrm-root-directory

- Now includes for hook_civicrm_inboundSMS

CRM-20238 - Add documentation for hook_civicrm_inboundSMS

Update inboundSMS Documenation as per updated CiviCRM Core PR #10347

Python script for hooks summary

Basics: File System -- Add section on composer, bower, packages

Autogenerate hooks summary (with Symfony CLI tool)

Done with:
./bin/tools generate:hook-list

- Keep the summary short
- Use a separate "Notes" section for overflow