minor #13899 Update ssi.rst Controller Paths (zairigimad)

This PR was submitted for the 5.0 branch but it was merged into the 4.4 branch instead.

Discussion
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Update ssi.rst Controller Paths

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Commits
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e2e183c Update ssi.rst

Author: javiereguiluz

http_cache/ssi.rst

@@ -114,7 +114,7 @@ The profile index page has not public caching, but the GDPR block has
     {# templates/profile/index.html.twig #}
 
     {# you can use a controller reference #}
-    {{ render_ssi(controller('App\Controller\ProfileController::gdpr')) }}
+    {{ render_ssi(controller('App\\Controller\\ProfileController::gdpr')) }}
 
     {# ... or a URL #}
     {{ render_ssi(url('profile_gdpr')) }}