Remove the wiki

Bloating the repository and not used or really required.

Emphasise source readability instead and encourage consumers to read the source to get API details.

The main documentation should be in README.md to describe the available resources and the fundamentals of building an Ardeidae app. This also means we can remove @param/@return docblock tags with move to PHP 7.4, since properties will now be typed too, so we can save lines and time and instead emphasise self-documenting source clarity using descriptions only.