Modules documentation is lacking

It should, for example, mention how to import a set of common QML components if the developer has a large QML application. The "Namespaces" section partially demonstrates this but the example should explicitly refer to custom components as well (e.g. if importing from a relative directory).

The "qmldir" section should link to examples to demonstrate its use (e.g. "plugins" and C++ extensions example). Additionally, other docs that refer to use of qmldir files should link to this documentation.

The introduction could also be improved - e.g. a module does not have to be a collection of types - it could be just a single file.