minor symfony#9144 Update form_csrf_caching.rst (tvlooy)

This PR was submitted for the 4.0 branch but it was merged into the 2.7 branch instead (closes symfony#9144).

Discussion
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Update form_csrf_caching.rst

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0a6ced4 Update form_csrf_caching.rst

Author: javiereguiluz

http_cache/form_csrf_caching.rst

@@ -36,7 +36,8 @@ Another option would be to load the form via an uncached AJAX request, but
 cache the rest of the HTML response.
 
 Or you can even load just the CSRF token with an AJAX request and replace the
-form field value with it.
+form field value with it. Take a look at :doc:`hinclude.js </templating/hinclude>`
+for a nice solution.
 
 .. _`Cross-site request forgery`: http://en.wikipedia.org/wiki/Cross-site_request_forgery
 .. _`Security CSRF Component`: https://github.com/symfony/security-csrf