Fixes #6207: Added support for truncating HTML strings using `StringHelper::truncate()` and `StringHelper::truncateWords()`

new private method `truncateHtml` now used by `truncate` and `truncateWords`

Improved comment about the meaning of "lte IE9"

"lte IE9" means IE9 or below, not above

fixes #3714
close #6186

docs/guide-pt-BR/images/application-structure.png - fixed size

close #6216

docs/guide-pt-BR/start-forms.md - translate

close #6218

docs/guide-pt-BR/start-databases.md - typo

close #6219

docs/guide-pt-BR/start-gii.md - typo/fixed

close #6221

docs/guide-pt-BR/start-looking-ahead.md - update

close #6222

docs/guide-pt-BR/structure-overview.md - typo

close #6223

docs/guide-pt-BR/structure-entry-scripts.md - typo

 close #6224

docs/guide-pt-BR/start-installation.md - typo/update

docs/guide/intro-upgrade-from-v1.md - fixed title reference

docs/guide-pt-BR/intro-upgrade-from-v1.md - typo/update

[skip ci] docs/guide-pt-BR/start-hello.md - typo

[skip ci] docs/guide-pt-BR/intro-yii.md - typo

[skip ci] docs/guide-pt-BR/README.md - update

docs/guide-ja/runtime-logging.md added [ci skip]

[ci skip] Update composer-asset-plugin version to beta4 in start-installation.md

[skip ci] Update db-migrations.md

Have not tested that beta4 works, honestly just trying out the GitHub edit button :P

Minor syntax changes.

fix entry scripts docs [skip ci]

Fixes #5504: Added note to yii\console\CacheController explaining that cache components should be configured in console app configuration in order to be cleared

[skip ci] Update db-active-record.md

Additional minor syntax changes.