fix: support old constructor

Author: achingbrain

.gitignore

@@ -2,6 +2,7 @@
 **/*.log
 test/repo-tests*
 **/bundle.js
+docs
 
 # Logs
 logs

README.md

@@ -36,7 +36,7 @@ const Room = require('ipfs-pubsub-room')
 const IPFS = require('ipfs')
 
 const ipfs = await IPFS.create({ ... })
-const room = Room(ipfs.libp2p, 'room-name')
+const room = Room(ipfs, 'room-name')
 ```
 
 Once we have a room we can listen for messages

src/index.js

@@ -18,7 +18,7 @@ let index = 0
 class PubSubRoom extends EventEmitter {
   constructor (libp2p, topic, options) {
     super()
-    this._libp2p = libp2p
+    this._libp2p = libp2p.libp2p || libp2p
     this._topic = topic
     this._options = Object.assign({}, clone(DEFAULT_OPTIONS), clone(options))
     this._peers = []