Add some helpful comments to type PeerID

peerid.go

@@ -4,8 +4,11 @@ import (
 	"encoding/hex"
 )
 
+// Peer client ID.
 type PeerID [20]byte
 
+// Pretty prints the ID as hex, except parts that adher to the Peer ID
+// Conventions of BEP 20.
 func (me PeerID) String() string {
 	if me[0] == '-' && me[7] == '-' {
 		return string(me[:8]) + hex.EncodeToString(me[8:])