Expand and correct build requirements in docs.

- Add Make and Clang requirements.
- Change ZeroMQ from 2.2 to 3.2 as zmq_sendmsg is used which is only found
  in the later version.
- State requirement for development packages of ZeroMQ and LibYAML.
Merge pull request #1 from apel/doc_improvement

Expand and correct build requirements in docs