minor #20797 fix: Change translation domain name for bundle translation and add an example (jbonnier)

This PR was merged into the 6.4 branch.

Discussion
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fix: Change translation domain name for bundle translation and add an example

The documentation was misleading regarding the bundle translations.

While the page [Symfony Bundles Documentation](https://symfony.com/doc/current/bundles.html) mentions that translation file names should use PascalCase — as shown in the example `AcmeBlogBundle.en.xlf` — the [Best Practices for Bundles](https://symfony.com/doc/current/bundles/best_practices.html#translation-files) suggest that the translation domain should be `acme_blog`.

This inconsistency led me to believe that there might be some mechanism that automatically converts the snake_case domain into PascalCase, but that isn’t the case.

I reviewed several bundles by core Symfony developers (such as EasyAdmin and bundles from SymfonyCasts), and they do indeed appear to use PascalCase translation domain names.

Commits
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20929b4 fix: Change translation domain name for bundle translation and add an example

Author: javiereguiluz

bundles/best_practices.rst

@@ -397,10 +397,14 @@ Translation Files
 -----------------
 
 If a bundle provides message translations, they must be defined in the XLIFF
-format; the domain should be named after the bundle name (``acme_blog``).
+format; the domain should be named after the bundle name (``AcmeBlog``).
 
 A bundle must not override existing messages from another bundle.
 
+The translation domain must match the translation file names. For example,
+if the translation domain is ``AcmeBlog``, the English translation file name
+should be ``AcmeBlog.en.xlf``.
+
 Configuration
 -------------