Merge pull request json-schema-org#19 from yuloh/patch-1

Add JSON Guard to the PHP implementations

Author: Relequestual

implementations.html

@@ -91,6 +91,7 @@ <h3>PHP</h3>
 		<li><a id="link-impl-php-json-schema" href="https://github.com/hasbridge/php-json-schema">php-json-schema</a> (MIT)</li>
 		<li><a id="link-impl-json-schema" href="https://github.com/justinrainbow/json-schema">json-schema</a> (Berkeley)</li>
 		<li><a id="link-impl-jvalidator" href="https://github.com/brainly/jvalidator">jvalidator</a> (BSD3)</li>
+		<li><a id="link-impl-json-guard" href="https://github.com/thephpleague/json-guard">JSON Guard</a> (MIT)</li>
 	</ul>
 
 	<h3>.NET</h3>