Extend qhelp references

Author: jorgectf

python/ql/src/experimental/Security/CWE-943/NoSQLInjection.qhelp

@@ -30,6 +30,10 @@
 <example>
 
 <references>
+  <li>Mongoengine: <a href="http://mongoengine.org/">Documentation</a>.</li>
+  <li>Flask-Mongoengine: <a href="http://docs.mongoengine.org/projects/flask-mongoengine/en/latest/">Documentation</a>.</li>
+  <li>PyMongo: <a href="https://pypi.org/project/pymongo/">Documentation</a>.</li>
+  <li>Flask-PyMongo: <a href="https://flask-pymongo.readthedocs.io/en/latest/">Documentation</a>.</li>
   <li>OWASP: <a href="https://owasp.org/www-pdf-archive/GOD16-NOSQL.pdf">NoSQL Injection</a>.</li>
   <li>Security Stack Exchange Discussion: <a href="https://security.stackexchange.com/questions/83231/mongodb-nosql-injection-in-python-code">Question 83231</a>.</li>
 </references>