Update README.md (#113)

chore: DEPR warning

README.md

@@ -1,3 +1,10 @@
+⛔️ WARNING
+==========
+
+This repository is under-maintained. We are not fixing bugs or developing new features for it. We hope to deprecate and replace it soon. For updates, [follow along on the DEPR ticket](https://github.com/openedx/public-engineering/issues/22)
+
+Although we have stopped integrating new contributions, we always appreciate security disclosures and patches sent to security@openedx.org
+
 xqueue_watcher
 ==========
 
@@ -153,4 +160,4 @@ grader.add_preprocessor(gradelib.wrap_in_string)
 grader.add_test(gradelib.ExecWrappedStudentCodeTest({}, "basic test"))
 ```
 
-You can also write your own test class, processor and input checks.
+You can also write your own test class, processor and input checks.