Rendering name for waterway=dock

[kocio-pl]

Resolves #2557.

Gdańsk, z17
Before

After

[imagico]

See #2701 - since i think we should drop rendering waterway=dock in general i also think we should not extend the current rendering. Especially incorrect use for mapping open harbor basins (like apparently in the example shown) would be encouraged by rendering labels.

[matthijsmelissen]

I agree this example is not a dock, either according to English language or according to osm's wiki.

[kocio-pl]

in general i also think we should not extend the current rendering.

This code is about rendering names with standard water label style, so I think it doesn't matter what kind of object it really is if it has a name and is related to water. I believe #2701 needs separate PR related to rendering water area, which is a different issue.