[e.cash] Reorder FAQ

Summary:
Content unchanged, just changing the order to put more relevant info near the top.

Content for specific questions and answers will be updated in further Diffs.

Test Plan: Ran it locally, looks good

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D14344