monitor: Update supported types documentation

Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

monitor.c

@@ -61,7 +61,9 @@
  * 'l'          target long (32 or 64 bit)
  * '/'          optional gdb-like print format (like "/10x")
  *
- * '?'          optional type (for 'F', 's' and 'i')
+ * '?'          optional type (for all types, except '/')
+ * '.'          other form of optional type (for 'i' and 'l')
+ * '-'          optional parameter (eg. '-f')
  *
  */