add PluginClientFactory comments (#83)

Author: fbourigault

src/PluginClientFactory.php

@@ -6,6 +6,9 @@
 use Http\Client\HttpClient;
 
 /**
+ * Factory to create PluginClient instances. Using this factory instead of calling PluginClient constructor will enable
+ * the Symfony profiling without any configuration.
+ *
  * @author Fabien Bourigault <bourigaultfabien@gmail.com>
  */
 final class PluginClientFactory
@@ -19,6 +22,8 @@ final class PluginClientFactory
      * Set the factory to use.
      * The callable to provide must have the same arguments and return type as PluginClientFactory::createClient.
      * This is used by the HTTPlugBundle to provide a better Symfony integration.
+     * Unlike the createClient method, this one is static to allow zero configuration profiling by hooking into early
+     * application execution.
      *
      * @internal
      *