Merge pull request #75 from overbool/docs/modify-readme

docs(README): modify readme

README.md

@@ -73,9 +73,19 @@ m1.Protocols()
 #### En/decapsulate
 
 ```go
-m.Encapsulate(ma.NewMultiaddr("/sctp/5678"))
+import ma "github.com/multiformats/go-multiaddr"
+
+m, err := ma.NewMultiaddr("/ip4/127.0.0.1/udp/1234")
+// <Multiaddr /ip4/127.0.0.1/udp/1234>
+
+sctpMA, err := ma.NewMultiaddr("/sctp/5678")
+
+m.Encapsulate(sctpMA)
 // <Multiaddr /ip4/127.0.0.1/udp/1234/sctp/5678>
-m.Decapsulate(ma.NewMultiaddr("/udp")) // up to + inc last occurrence of subaddr
+
+udpMA, err := ma.NewMultiaddr("/udp/1234")
+
+m.Decapsulate(udpMA) // up to + inc last occurrence of subaddr
 // <Multiaddr /ip4/127.0.0.1>
 ```