pmdalinux: fix typo in disk.all.aveq metric help text
pmdalinux: fix typo in disk.all.aveq metric help text

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