Reference: Hooks (#19)

[fritzmg]

• add all hooks from the previous documentation
• check if some hooks do not exist anymore
• check if some hooks are missing
• add parameter definition to each hook
• add deprecation warnings
• use Contao 4.8 annotations instead of service tagging

[fritzmg]

It is finally done.

• Previously missing hooks have been added.
• Previously undocumented hooks got their documentation.
• All hooks now describe their parameters and return values.
• All examples are now in a unified format using the App\EventListener namespace and annotations.
• All code references have been updated (currently with links to Contao 4.7.6 and one instance with Contao 4.8.0-RC1).
• I removed the addFileMetaInformationToRequest hook. While the hook is technically still there, the function is not used by Contao at all anymore. If necessary, we can still add it of course.
• All deprecated hooks are described as such.
• Instead of the See also approach of the previous documentation I am now using the taxonomy feature of Hugo and each hook is now appropriately tagged, so that you can quickly find related hooks with the same tag. Tags for hooks start with hook-. Hugo also provides an overview page for all used tags under the /tags/ path (however, that would contain all tags, not just those for hooks).
• References also contain links to GitHub issues or pull requests when applicable.
• The example section also contain links to the Contao bundles whenever the Contao bundles use any hooks themselves.
• I improved the description of some of the hooks - but there is still a lot of room for improvement for all hooks.
• All hook examples and parameters have been checked for mistakes and their accuracy. There could still be errors of course ;)
• I also improved the main menu. Level 3 items will now only be shown, if their parent is active. Level 3 is hidden for the hook reference altogether, since the list is far too long. Navigation can be down via the main hook reference page, tags and the left/right navigation.