Create blog post explaining the iOS migration from NC Apple Account to OHF Apple Account

### Description

Prepare a blog post explaining user why the app is being migrated, what options they will have and what will not migrate from one app to the other, as well as timelines, deadline and overall impact.

### Additional context

_No response_

Begin by gathering the migration rationale, available user options, non-migrating data, timeline, deadlines, and overall impact from the iOS migration work. The task is done when a blog post clearly explains these points to affected users and sets out what they need to do.

Written by the indexing model from the issue text.