Merge pull request #5577 from PeterKietzmann/tests_thread_exti_doc

tests/thread_exti: add small README

tests/thread_exit/README.md

+Expected result
+===============
+You should see the following sequence at the console
+
+main: starting
+main: exiting
+2nd: starting
+3rd: starting
+3rd: exiting
+2nd: exiting
+4th: starting
+4th: exiting

tests/thread_exit/main.c

@@ -69,7 +69,7 @@ void *second_thread(void *arg)
              NULL,
              "nr4")
         ) == -1) {
-        puts("2nd: Error creating 4rd thread.");
+        puts("2nd: Error creating 4th thread.");
     }
 
     puts("2nd: exiting");
@@ -89,7 +89,7 @@ int main(void)
              NULL,
              "nr2")
         ) == -1) {
-        puts("main: Error creating 3rd thread.");
+        puts("main: Error creating 2nd thread.");
     }
 
     puts("main: exiting");