minor #20431 fix: Update micro_kernel_trait.rst (m0rff)

This PR was merged into the 7.2 branch.

Discussion
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fix: Update micro_kernel_trait.rst

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Commits
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a0f7fab fix: Update micro_kernel_trait.rst

Author: javiereguiluz

configuration/micro_kernel_trait.rst

@@ -16,7 +16,7 @@ via Composer:
 
 .. code-block:: terminal
 
-    $ composer symfony/framework-bundle symfony/runtime
+    $ composer require symfony/framework-bundle symfony/runtime
 
 Next, create an ``index.php`` file that defines the kernel class and runs it: