chore: document validators, fix caching issue

docs/pages/docs/features/validation/constraints/index.md

docs/pages/docs/features/validation/form-models/index.md

...s/features/validation/http-controller-parameters/index.md

docs/pages/docs/features/validation/index.md

src/Command/StaticPagesBuild.php

src/Command/StaticPagesDumpContent.php

src/Command/StaticPagesMakeEmbeddings.php

src/Feature.php

src/InputValidator/FrontMatterValidator.php

src/InputValidatorController.php

src/SingletonProvider/InputValidatorCollectionProvider.php

src/SingletonProvider/InputValidatorControllerProvider.php

src/StaticPageChunkIterator.php

src/StaticPageContentRenderer.php

src/StaticPageMarkdownParser.php

src/StaticPageProcessor.php

src/StaticPageSitemapGenerator.php