Enhance Criterion\LanguageCode example

[adriendupuis]

Question	Answer
JIRA Ticket	N/A
Versions	4.6, master
Edition	All

A clarified specification could be available in https://issues.ibexa.co/browse/IBX-9303

• Add another …\Content\Query\Criterion\LanguageCode use case.
• Use …\Content\Query with SearchService::findContent() instead of …\Content\LocationQuery.

Preview:

• Before: https://doc.ibexa.co/en/latest/search/criteria_reference/languagecode_criterion/#use-case
• After: https://ez-systems-developer-documentation--2550.com.readthedocs.build/en/2550/search/criteria_reference/languagecode_criterion/#use-cases

Checklist

• [ ] Text renders correctly
• [ ] Text has been checked with vale
• [ ] Description metadata is up to date
• [ ] Redirects cover removed/moved pages
• [ ] Code samples are working
• [ ] PHP code samples have been fixed with PHP CS fixer
• [ ] Added link to this PR in relevant JIRA ticket or code PR