[docs] provide rules for correct usage of events, mutexes, and timers
diff --git a/include/kernel/mutex.h b/include/kernel/mutex.h
index 2bdf8f4..40fe72f 100644
--- a/include/kernel/mutex.h
+++ b/include/kernel/mutex.h
@@ -34,6 +34,11 @@
 	wait_queue_t wait;
 } mutex_t;
 
+/* Rules for Mutexes:
+ * - Mutexes are only safe to use from thread context.
+ * - Mutexes are non-recursive.
+*/
+
 void mutex_init(mutex_t *);
 void mutex_destroy(mutex_t *);
 status_t mutex_acquire(mutex_t *);