DOC Add Twitter link to README.rst (scikit-learn#17891)

Author: alfaro96

README.rst

@@ -163,6 +163,7 @@ Communication
 - Mailing list: https://mail.python.org/mailman/listinfo/scikit-learn
 - IRC channel: ``#scikit-learn`` at ``webchat.freenode.net``
 - Gitter: https://gitter.im/scikit-learn/scikit-learn
+- Twitter: https://twitter.com/scikit_learn
 - Stack Overflow: https://stackoverflow.com/questions/tagged/scikit-learn
 - Website: https://scikit-learn.org