add further resources

transforms/language/doc_quality/python/README.md

@@ -102,6 +102,17 @@ Currently we have:
 - [Unit test](test/test_doc_quality_python.py)
 - [Integration test](test/test_doc_quality.py)
 
+
+## Further Resource
+
+- For those who want to learn C4 heuristic rules
+  - https://arxiv.org/pdf/1910.10683.pdf
+- For those who want to learn Gopher statistics
+  - https://arxiv.org/pdf/2112.11446.pdf
+- For those who want to see the source of badwords used by default
+  - https://github.com/LDNOOBW/List-of-Dirty-Naughty-Obscene-and-Otherwise-Bad-Words
+
+
 ## Consideration
 
 ### Troubleshooting guide