Update README.md

README.md

@@ -28,4 +28,68 @@ The bootstrapper creates a new libp2p node, subscribes to the shared topic strin
 
 (Note that the node ID of `pubsub-interop` is going to be `Qm...6aJ9oRuEzWa`.  Node IDs in libp2p are just public keys, and the public key `Qm...6aJ9oRuEzWa` is derived from the private key file `../util/private_key.bin.bootstrapper.Wa`.  That file is just an X.509 keypair generated by the included program `util/private-key-gen`).  We use fixed public/private keypairs for each node in this example to keep things simple.)
 
+**Second terminal**:  Create a go peer to connect to bootstrapper and publish on the topic
+
+```
+cd pubsub
+./pubsub-interop ../util/private_key.bin.peer.Sk
+```
+
+This peer, which is not in bootstrapper mode, creates a node, subscribes to the shared topic string, spawns the same go routine, and then loops forever requesting user input and publishing each line to the topic.
+
+**Third terminal**:  Create another go peer to connect to bootstrapper and publish on the topic
+
+```
+cd pubsub
+./pubsub-interop ../util/private_key.bin.peer.vy
+```
+
+
+
+**Fourth terminal**:  Create a JS peer to connect to bootstrap and publish on topic
+
+```
+cd pubsub/js
+npm install  # first time only
+node index.js /ip4/127.0.0.1/tcp/5555/ipfs/QmehVYruznbyDZuHBV4vEHESpDevMoAovET6aJ9oRuEzWa
+```
+
+This JS peer will accept lines of text typed on stdin, and publish them on the PubSub topic.
+
+(Note that the JS peer generates a new identity (public/private keypair) each time, and prints its public key to stdout.  This is a deficiency in the demo; to be consistent with the Go code it should accept a private key on the CLI.)
+
+
+If you return to the second, third or fourth terminals and type a message, the bootstrapper and the other 2 peers will all print your message.
+
+**Conclusion**
+
+You now have a chat app on a private libp2p network where each node can exchange messages anonymously using PubSub.
+
+## Debugging Notes
+
+**JS** To see debug messages from the Node.js program, use the `DEBUG` environment variable:
+```
+DEBUG="libp2p:floodsub*,libp2p:switch*,mss:*" node index.js [args...]
+```
+
+**Go** To see debug messages in Go programs, do this at runtime:
+```
+IPFS_LOGGING=debug ./pubsub-interop [args...]
+```
+
+(**TODO**:  describe custom instrumenting the local go code for complex debugging)
+
+If you instrument your go code with custom `fmt.Println`'s, then revert back like this:
+```
+cd $GOPATH
+go get -u ./...
+```
+
+Other useful commands:
+```
+go get -u github.com/libp2p/go-libp2p-kad-dht   # fetch just Kad DHT repo
+```
+
+
+_Acknowledgements:  @jhiesey for DHT (content & peer routing) JS+Go interop, @stebalien for PubSub_