minor symfony#15767 Fix a minor RST syntax issue (javiereguiluz)

This PR was merged into the 5.3 branch.

Discussion
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Fix a minor RST syntax issue

Commits
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dccdc16 Fix a minor RST syntax issue

Author: javiereguiluz

routing.rst

@@ -2369,6 +2369,7 @@ session shouldn't be used when matching a request:
 
 Now, if the session is used, the application will report it based on your
 ``kernel.debug`` parameter:
+
 * ``enabled``: will throw an :class:`Symfony\\Component\\HttpKernel\\Exception\\UnexpectedSessionUsageException` exception
 * ``disabled``: will log a warning