minor #13478 Fixes wrong tag for RouteLoaderInterface registration without autoconfiguration (pounard)

This PR was merged into the 4.4 branch.

Discussion
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Fixes wrong tag for RouteLoaderInterface registration without autoconfiguration

Following #13474

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Commits
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13a92be Fixes wrong tag for RouteLoaderInterface registration without autoconfiguration

Author: javiereguiluz

routing/custom_route_loader.rst

@@ -214,7 +214,7 @@ extend or implement any special class, but the called method must return a
 If you're using :ref:`autoconfigure <services-autoconfigure>`, your class should
 implement the :class:`Symfony\\Bundle\\FrameworkBundle\\Routing\\RouteLoaderInterface`
 interface to be tagged automatically. If you're **not using autoconfigure**,
-tag it manually with ``routing.loader``.
+tag it manually with ``routing.route_loader``.
 
 .. deprecated:: 4.4