doc: Create a privacy policy for the PeerJS server

This adds a very simply privacy policy for PeerJS servers.

Closes peers/peerjs#649

PRIVACY.md

@@ -0,0 +1,10 @@
+# Privacy Policy
+
+**We do not collect or store any information.**
+
+While you are connected to a PeerJS server, your IP address, randomly-generated
+client ID, and signalling data are kept in the server's memory.  With default
+settings, the server will remove this information from memory 60 seconds after
+you stop communicating with the service.  (See the
+[`alive_timeout`](https://github.com/peers/peerjs-server#config--cli-options)
+setting.)

README.md

@@ -223,6 +223,10 @@ This will start a peerjs server on port 9000 exposed on port 9000 with key `peer
 
 Open your browser with http://localhost:9000/myapp It should returns JSON with name, description and website fields. http://localhost:9000/myapp/peerjs/id - should returns a random string (random client id)
 
+## Privacy
+
+See [PRIVACY.md](https://github.com/peers/peerjs-server/blob/master/PRIVACY.md)
+
 ## Problems?
 
 Discuss PeerJS on our Telegram chat: