Mention PHP bindings to libbitcoinconsensus

Author: afk11

doc/shared-libraries.md

@@ -41,3 +41,4 @@ The interface is defined in the C header `bitcoinconsensus.h` located in  `src/s
 - [NBitcoin](https://github.com/NicolasDorier/NBitcoin/blob/master/NBitcoin/Script.cs#L814) (.NET Bindings)
 - [node-libbitcoinconsensus](https://github.com/bitpay/node-libbitcoinconsensus) (Node.js Bindings)
 - [java-libbitcoinconsensus](https://github.com/dexX7/java-libbitcoinconsensus) (Java Bindings)
+- [bitcoinconsensus-php](https://github.com/Bit-Wasp/bitcoinconsensus-php) (PHP Bindings)