In the future need will need to continue to tie qdoc runs still to
targets, just like with qmake. This change prepares us for that by
ensuring that add_docs takes two parameters and that any re-generated
CMakeLists.txt from now on gets it right.
Change-Id: Id0256dc1e2f2f59f3b4e4ca98f0d10d025d189fb
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>