Add How to Backup Database

[mrwul]

Regularly when a new version is introduced a remark is added

//
Database has been improved, PLEASE make an backup of it before to install this version
//

As a tip, maybe add 'How to' do that' there '?

Actually I never backup database as such. XnViewMP is being backup'ed during the weekly backup routine.
That said, I was looking how to backup the database from within XnviewMP.
(Would expect something under 'Tools' or 'File')

[xnview]

In About dialog, you have the pathname used for .ini and .db
So you can save them before you update XnViewMP