Update examples

Author: pyropy

example/README.md

@@ -2,10 +2,10 @@
 
 ### Encrypting the file
 ```
-go run example/main.go -action=encrypt -in=bitcoin.pdf -out=bitcoin-enc.pdf -hash=00000000000000000000000000000000000000 -preimage=0000000000000000000000000000000000000000 
+go run example/main.go -action=encrypt -in=bitcoin.pdf -out=bitcoin-enc.pdf -hash=84645f0ccdd6f4695d655b3b6e8dfe6f4f35ad55fac62981c98216d74f87bae5 -preimage=28a794564e8c20a64b6376c4ebdd84ae3525f45342b957f9334f6fdb86c7615d 
 ```
 
 #### Decrypting the file
 ```
-go run example/main.go -action=decrypt -in=bitcoin-enc.pdf -out=bitcoin-dec.pdf -hash=00000000000000000000000000000000000000 -preimage=0000000000000000000000000000000000000000 
+go run example/main.go -action=decrypt -in=bitcoin-enc.pdf -out=bitcoin-dec.pdf -hash=84645f0ccdd6f4695d655b3b6e8dfe6f4f35ad55fac62981c98216d74f87bae5 -preimage=28a794564e8c20a64b6376c4ebdd84ae3525f45342b957f9334f6fdb86c7615d 
 ```

example/main.go

@@ -100,7 +100,12 @@ func decrypt(inPath, outPath, preimage string, chunkSize int64) error {
 		return err
 	}
 
-	decryptedFile, index, err := bitstream.Decrypt(preimageBytes, f, chunkSize)
+	paymentHashBytes, err := hex.DecodeString(paymentHash)
+	if err != nil {
+		return err
+	}
+
+	decryptedFile, index, err := bitstream.Decrypt(paymentHashBytes, preimageBytes, f, chunkSize)
 	if err != nil {
 		if index != -1 {
 			proof, err := bitstream.GenerateProof(f, chunkSize, 2*index)