Link to Howto page in ecloud 2FA activation form

When activating 2FA in ecloud, it would be helpful for users to have a quick access to the guide on the matter.

Summary

Add a link (maybe a question mark icon so we skip localization) to the documentation in this section:

Description

What is the current behavior?

When users enable 2FA, they cannot use the main password to connect an e.email account on the phone. They need to generate an app password. Users may not know this.

What is the improved behavior?

• A help button/link pointing to the complete documentation on this topic, which is quite complex.
• A note right after the introduction to draw the attention of the user to the usage with an /e/ account on his/her device:

Use a second factor besides your password to increase security for your account.

Note: You'll need to create a new application password to set your account within /e/OS. Additionally, you need to provide your main account password to /e/OS Mail.