New section on encrypted file storage services - Files Tools

E2E file storage services should be added to the list of tools to protect sensitive files.

Add to new section on collaboration + relevant tools sub-section

and link from https://securityinabox.org/en/files/secure-file-storage/#store-to-an-encrypted-cloud-account

also add to this list: https://gitlab.com/securityinabox/securityinabox.gitlab.io/-/tree/main/src/files/backup#encrypted-cloud-services

name	url	features	free plan
Internxt	https://internxt.com/drive	open source E2E audited	free plan up to 10GB
Proton Drive	https://proton.me/drive	https://proton.me/drive/security https://proton.me/blog/protondrive-security	5 GB free cloud storage
Skiff Drive	https://skiff.com/drive	https://skiff.com/security-model	10GB free storage
Filen	https://filen.io/	https://filen.io/encryption	10GB free storage
Nextcloud	https://nextcloud.com/	https://nextcloud.com/encryption/	self-hosted or https://nextcloud.com/providers/
Cryptpad	https://cryptpad.fr/	https://docs.cryptpad.org/en/user_guide/security.html	self-hosted or https://cryptpad.org/instances/