Add message factory installation to socket client docs

Márk Sági-Kazár · shulard · commit c7de09af8d4f · 2016-02-18T11:18:44.000+01:00
diff --git a/clients/socket-client.rst b/clients/socket-client.rst
@@ -21,6 +21,8 @@ To install the Socket client, run:
 
     $ composer require php-http/socket-client
 
+.. include:: includes/install-message-factory.inc
+
 Usage
 -----
 
