⭐ [Documentation] - Add FAQ on limiting how far back bank sync looks

[psybers]

Description

Users often want to limit how far back the bank sync pulls data. The advice is to set a starting balance on the date you want to limit it syncing from. We should update the FAQ to include guidance on this.

Documentation URL

https://github.com/actualbudget/docs/blob/master/docs/advanced/bank-sync.md