minor #17244 Method getCharset with proper returning type (githubfromgui)

This PR was merged into the 4.4 branch.

Discussion
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Method getCharset with proper returning type

The method `getCharset` implemented by the example should return `string` type, like the `Symfony\Component\HttpKernel\Kernel` abstract class requires:

![image](https://user-images.githubusercontent.com/5428251/187910885-5a1fbde9-69c3-4c5e-88fd-d08958bfbd72.png)

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Commits
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80034dd Method getCharset with proper returning type

Author: javiereguiluz

reference/configuration/kernel.rst

@@ -33,7 +33,7 @@ charset::
 
     class Kernel extends BaseKernel
     {
-        public function getCharset()
+        public function getCharset(): string
         {
             return 'ISO-8859-1';
         }