minor #11100 [Mercure] Fix list rendering (dunglas)

This PR was merged into the 4.2 branch.

Discussion
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[Mercure] Fix list rendering

Fixes a tiny rendering flitch.

Commits
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ce14444 [Mercure] Fix list rendering

Author: javiereguiluz

mercure.rst

@@ -221,6 +221,7 @@ and to use URI Templates as patterns:
     .. image:: /_images/mercure/chrome.png
 
     To use it:
+
     * open the DevTools
     * select the "Network" tab
     * click on the request to the Mercure hub