doc: allow notes on Param API Reference pages
    
    The notes that Param pages will contain after #6733 are added manually,
    and because of it we need to add markers to differentiate between
    automated and manual content, equal to what we do for class pages.
    
    Signed-off-by: Antonio Torres <antorres@redhat.com>
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>
    Reviewed-By: Rob Crittenden <rcritten@redhat.com>