Fix FAQ: No need to delete stored emails to fix "UID validity problem"

[Keith David Bershatsky]

Please correct the FAQ so that users are not led to believe that they should delete the stored emails to fix an error message relating to:

"UID validity problem for folder INBOX (repo name-remote) (saved 359005952; got 1472566705); skipping it. Please see FAQ and manual on how to handle this."

All that is needed is to delete the sqlite corresponding box along with the local and remote FolderValidity boxes.  The data (which may be several gigabytes of stored emails) does not need to be deleted and re-downloaded.

Thanks.

Keith