Equeue chain, add documentation of using equeue_destroy

TESTS/events/equeue/main.cpp

@@ -742,8 +742,8 @@ static void test_equeue_chain()
     TEST_ASSERT_EQUAL_UINT8(3, touched1);
     TEST_ASSERT_EQUAL_UINT8(3, touched2);
 
-    equeue_destroy(&q1);
     equeue_destroy(&q2);
+    equeue_destroy(&q1);
 }
 
 /** Test that unchaining equeues makes them work on their own.

UNITTESTS/events/equeue/test_equeue.cpp

@@ -765,8 +765,8 @@ TEST_F(TestEqueue, test_equeue_chain)
     EXPECT_EQ(3, touched1);
     EXPECT_EQ(3, touched2);
 
-    equeue_destroy(&q1);
     equeue_destroy(&q2);
+    equeue_destroy(&q1);
 }
 
 /** Test that unchaining equeues makes them work on their own.

events/equeue.h

@@ -93,6 +93,9 @@ typedef struct equeue {
 //
 // If the event queue creation fails, equeue_create returns a negative,
 // platform-specific error code.
+//
+// If queues are chained, it is needed to unchain them first, before calling destroy,
+// or call the destroy function on queues in order that chained queues are destroyed first.
 int equeue_create(equeue_t *queue, size_t size);
 int equeue_create_inplace(equeue_t *queue, size_t size, void *buffer);
 void equeue_destroy(equeue_t *queue);

events/source/tests/tests.c

@@ -606,8 +606,8 @@ void chain_test(void)
 
     test_assert(touched == 6);
 
-    equeue_destroy(&q1);
     equeue_destroy(&q2);
+    equeue_destroy(&q1);
 }
 
 void unchain_test(void)