docs: remove beta info status from index page

docs/src/ar/index.md

docs/src/br/index.md

docs/src/ca/index.md

docs/src/de/index.md

docs/src/el/index.md

docs/src/es/index.md

docs/src/fa/index.md

docs/src/fr/index.md

docs/src/gd/index.md

docs/src/gl/index.md

docs/src/id/index.md

docs/src/index.md

docs/src/it/index.md

docs/src/ko/index.md

docs/src/nl/index.md

docs/src/nn-NO/index.md

docs/src/oc/index.md

docs/src/pl/index.md

docs/src/pt-BR/index.md

docs/src/pt/index.md