update readme and virtualenv

README.md

@@ -1 +1,11 @@
 # py-libp2p
+
+## Development
+
+py-libp2p requires Python 3.6 and the best way to guarantee a clean Python 3.6 environment is with [`virtualenv`](https://virtualenv.pypa.io/en/stable/)
+
+```sh
+virtualenv -p python3.6 venv
+. venv/bin/activate
+pip install -r requirements.txt
+```