dub is building docs of dependencies

[Jedzia]

Okay, what i am trying to achieve is simply not there.

BuildOption._docs is a enum, that is passed recursively to the 
dependencies and switches doc building on and object building off 
for the different generators (I missed to say that i am using dmd 
-> "-o-", "-Dddocs").

What i was looking for is a dub command-target like "build", 
"run", "test".

Oh .... "add docs command" -> 
https://github.com/dlang/dub/issues/501

Not a solution, but a warm feeling of knowledge:)