Merge pull request #6338 from larnu/master

spanish docs structure-extensions [skip ci]
updated docs about plural rules

fixes #6321
added code hightlight
Improved description of how Yii handles plural rules
docs/guide/runtime-routing.md - fix [ci skip]
Merge pull request #6340 from softark/docs-guide-fix

docs/guide/runtime-routing.md - fix [ci skip]
further imrpovements to plural rules
docs/guide-ja/runtime revised [ci skip]

close #6341
Error in documentation

Method clientLink no returns data. In the example of the use of manual output clients in the loop you need to use <?php instead of <?=
Merge pull request #6342 from PiloTeZ/patch-1

[skip ci] Error in documentation
added support for DateTimeImmutable to Formatter

fixes #5503