docs: pmdaprometheus man page - added scripted config examples
docs: pmdaprometheus man page - added scripted config examples

Added some examples and clarified description of subdirectory
handling and scripted config entries.

adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp