docs(examples): add P2PKH validation example (#38)

Author: mrz1836

examples/example.go

@@ -1,4 +1,31 @@
 // Package examples provides example code for various functionalities.
 package examples
 
-// TODO - add example code here
+import (
+	"fmt"
+	"os"
+
+	chaincfg "github.com/bsv-blockchain/go-chaincfg"
+	"github.com/bsv-blockchain/go-wire"
+)
+
+// ExampleIsPubKeyHashAddrID demonstrates how to verify the legacy public key hash
+// (P2PKH) address identifier bytes for a specific Bitcoin SV network.
+//
+// The helper reports whether the provided identifier is valid for the supplied
+// network magic value. This is useful when parsing external configuration or
+// performing sanity checks on user-supplied address metadata.
+func ExampleIsPubKeyHashAddrID() {
+	write := func(value bool) {
+		if _, err := fmt.Fprintf(os.Stdout, "%t\n", value); err != nil {
+			panic(err)
+		}
+	}
+
+	write(chaincfg.IsPubKeyHashAddrID(wire.MainNet, chaincfg.MainNetParams.LegacyPubKeyHashAddrID))
+	write(chaincfg.IsPubKeyHashAddrID(wire.MainNet, chaincfg.TestNetParams.LegacyPubKeyHashAddrID))
+
+	// Output:
+	// true
+	// false
+}