Add bitwasp bitcoin php library

ch03.asciidoc

@@ -774,6 +774,9 @@ https://github.com/bitcoinjs/bitcoinjs-lib[BitcoinJS] :: A pure JavaScript Bitco
 https://bitcoinj.github.io[bitcoinj]:: A Java full-node client library
 https://bitsofproof.com[Bits of Proof (BOP)]:: A Java enterprise-class implementation of bitcoin
 
+==== PHP
+https://github.com/bit-wasp/bitcoin-php[bitwasp/bitcoin]:: A PHP bitcoin library, and related projects
+
 ==== Python
 https://github.com/petertodd/python-bitcoinlib[python-bitcoinlib]::  A Python bitcoin library, consensus library, and node by Peter Todd
 https://github.com/richardkiss/pycoin[pycoin]:: A Python bitcoin library by Richard Kiss