Don't duplicate -doc package contents in base package (#913540).
    
    - Define and use %_pkgdocdir as suggested by the Unversioned Docdirs
      change for Fedora 20 (#993908).
    - Pass --docdir= to waf.
    - Use Group Documentation in -doc subpackage.
    - Rename -docs package to -doc as recommended in the guidelines.
    - The documentation subpackage does not need the base package.