Fix documentation code examples.

The examples uses a btcutil API that was recently updated from passing
btcwire.BitcoinNet to *btcnet.Params.  This change updates the btcutil
call in the examples, as well as modifying the example in the README
to match that in doc.go (where errors were handled slightly
differently).

README.md

@@ -20,6 +20,7 @@ package main
 import (
 	"flag"
 	"fmt"
+	"log"
 
 	"github.com/conformal/btcnet"
 	"github.com/conformal/btcutil"
@@ -42,10 +43,9 @@ func main() {
 
 	// Create and print new payment address, specific to the active network.
 	pubKeyHash := make([]byte, 20)
-	addr, err := btcutil.NewAddressPubKeyHash(pubKeyHash, netParams.Net)
+	addr, err := btcutil.NewAddressPubKeyHash(pubKeyHash, netParams)
 	if err != nil {
-		// badness
-		return
+		log.Fatal(err)
 	}
 	fmt.Println(addr)
 }

doc.go

@@ -48,7 +48,7 @@
 //
 //          // Create and print new payment address, specific to the active network.
 //          pubKeyHash := make([]byte, 20)
-//          addr, err := btcutil.NewAddressPubKeyHash(pubKeyHash, netParams.Net)
+//          addr, err := btcutil.NewAddressPubKeyHash(pubKeyHash, netParams)
 //          if err != nil {
 //                  log.Fatal(err)
 //          }