Added function comment

mysys/thr_alarm.c

@@ -122,9 +122,21 @@ void init_thr_alarm(uint max_alarms)
 
 /*
   Request alarm after sec seconds.
-  A pointer is returned with points to a non-zero int when the alarm has been
-  given. This can't be called from the alarm-handling thread.
-  Returns 0 if no more alarms are allowed (aborted by process)
+
+  SYNOPSIS
+    thr_alarm()
+    alrm		Pointer to alarm detection
+    alarm_data		Structure to store in alarm queue
+
+  NOTES
+    This function can't be called from the alarm-handling thread.
+
+  RETURN VALUES
+    0 ok
+    1 If no more alarms are allowed (aborted by process)
+
+    Stores in first argument a pointer to a non-zero int which is set to 0
+    when the alarm has been given
 */
 
 my_bool thr_alarm(thr_alarm_t *alrm, uint sec, ALARM *alarm_data)