minor #11104 [Mercure] Link to the English version of MDN (dunglas)

This PR was merged into the 4.2 branch.

Discussion
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[Mercure] Link to the English version of MDN

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53f9fbe [Mercure] Link to the English version of MDN

Author: javiereguiluz

mercure.rst

@@ -530,7 +530,7 @@ Checkout `the dedicated API Platform documentation`_ to learn more about
 its Mercure support.
 
 .. _`the Mercure protocol`: https://github.com/dunglas/mercure#protocol-specification
-.. _`Server-Sent Events (SSE)`: https://developer.mozilla.org/fr/docs/Server-sent_events
+.. _`Server-Sent Events (SSE)`: https://developer.mozilla.org/docs/Server-sent_events
 .. _`a polyfill`: https://github.com/Yaffle/EventSource
 .. _`high-level implementations`: https://github.com/dunglas/mercure#resources
 .. _`In this recording`: https://www.youtube.com/watch?v=UI1l0JOjLeI