chore: connection encryption example test (#843)

examples/connection-encryption/README.md

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+# Connection Encryption
+
+libp2p can leverage the encrypted communications from the transports it uses (i.e WebRTC). To ensure that every connection is encrypted, independently of how it was set up, libp2p also supports a set of modules that encrypt every communication established.
+
+We call this usage a _connection upgrade_ where given a connection between peer A to peer B, a protocol handshake can be performed that gives that connection new properties.
+
+A byproduct of having these encrypted communications modules is that we can authenticate the peers we are dialing to. You might have noticed that every time we dial to a peer in libp2p space, we always use its PeerId at the end (e.g /ip4/127.0.0.1/tcp/89765/p2p/QmWCbVw1XZ8hiYBwwshPce2yaTDYTqTaP7GCHGpry3ykWb), this PeerId is generated by hashing the Public Key of the peer. With this, we can create a crypto challenge when dialing to another peer and prove that peer is the owner of a PrivateKey that matches the Public Key we know.
+
+# 1. Set up encrypted communications
+
+We will build this example on top of example for [Protocol and Stream Multiplexing](../protocol-and-stream-multiplexing). You will need the `libp2p-noise` module to complete it, go ahead and `npm install libp2p-noise`.
+
+To add them to your libp2p configuration, all you have to do is:
+
+```JavaScript
+const Libp2p = require('libp2p')
+const { NOISE } = require('libp2p-noise')
+
+const createNode = () => {
+  return Libp2p.create({
+    modules: {
+      transport: [ TCP ],
+      streamMuxer: [ Mplex ],
+      // Attach noise as the crypto channel to use
+      connEncryption: [ NOISE ]
+    }
+  })
+}
+```
+
+And that's it, from now on, all your libp2p communications are encrypted. Try running the example [1.js](./1.js) to see it working.