FAQ – Hide/Show content by platform (iOS, Android, Desktop)

[changecourse]

Acceptance Criteria:

• hide all but one platform at a time (of the three we need to support for a given section)
• be able to anchor link to different nested sections, e.g., "How to Enable sync (iOS active)"

We need to provide a way to collapse some of the content on the FAQ to make it more easily scannable for users, and so they do not need to scroll through platform content that does not apply to their use case (e.g., "How do I perform a manual sync?" while on Android, the user does not need to be presented with steps and screenshots for iOS and Desktop.)