Notably:
* `Packed*Array.size()` and `Array.size()`.
* Shared methods of `Transform2D` and `Transform3D`.
* Shared methods of `Vector2`, `Vector3`, and `Vector2i`.
This reduces the Deja Vu when translating the class reference :)
For the time being we don't support writing a description for those, preferring
having all details in the method's description.
Using self-closing tags saves half the lines, and prevents contributors from
thinking that they should write the argument or return documentation there.
