intro upgrade from v1 guide translated

Create caching-page.md

French start-installation.md

Fix typo in start-installation.md

fixes #3891

Translation es

English guide small fix [skip ci]

Translate "Page Caching"

docs about file validator fixed

Spanish guide polish and start-looking-head.md [skip ci]

to be adjusted while translating chapters.

type validation adjusted

Fix in start-hello.md and spanish translation of start-forms.md

Create db-active-record.md