doc/perfevent: Additional info regarding dynamic events
doc/perfevent: Additional info regarding dynamic events

Signed-off-by: Hemant Kumar <7123f6a6628a9fc84f20db1d8af7bbec27c94c78@linux.vnet.ibm.com>

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