mention framework integration in users intro

Author: dbu

httplug/users.rst

@@ -13,6 +13,9 @@ you plan to use:
 
     composer require php-http/curl-client guzzlehttp/psr7 php-http/message
 
+If you use a framework, check the :doc:`integrations <integrations>` overview to
+see if there is a plugin for your framework.
+
 Details
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