update README

Author: chyyuu

README.md

@@ -50,5 +50,8 @@ According to the  [Guide](https://learningos.github.io/rust-based-os-comp2022/),
 - lab4: `make test6`  &&  `make test7` for lab4 
 - lab5: `make test8`  for lab5 
 
-## Send issues
-If  you meet any problems or some difficulties, please send issues to [Issues in rust-based-os-comp2022](https://github.com/LearningOS/rust-based-os-comp2022/issues)
+## QA &Send issues
+
+There are some methods for common questions & problems, please read [QA](./QA.md).
+
+If  you meet any other new problems or some difficulties, please send issues to [Issues in rust-based-os-comp2022](https://github.com/LearningOS/rust-based-os-comp2022/issues)