minor #18279 Update multiple_kernels.rst (yceruto)

This PR was merged into the 5.4 branch.

Discussion
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Update multiple_kernels.rst

Replacing tabs with spaces

![image](https://user-images.githubusercontent.com/2028198/236287985-a969bab4-c39e-4b84-b409-12a3fea02c82.png)

Commits
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397e74f Update multiple_kernels.rst

Author: javiereguiluz

configuration/multiple_kernels.rst

@@ -62,16 +62,16 @@ directory structure like the one described in :ref:`Symfony Best Practice </best
     │  └─ api/
     │     ├─ config/
     │     │  ├─ bundles.php
-    │	  │  ├─ routes.yaml
-    │	  │  └─ services.yaml
-    │  	  └─ src/
+    │     │  ├─ routes.yaml
+    │     │  └─ services.yaml
+    │     └─ src/
     ├─ bin/
     │  └─ console
     ├─ config/
     ├─ public/
     │  └─ index.php
     ├─ src/
-    │	└─ Kernel.php
+    │  └─ Kernel.php
 
 .. note::