Improved the FQDN check and Ask before changing Git Repository URL in "update.sh"

[AlexHuebi]

I've added a check for if the last letter in MAILCOW_HOSTNAME is a dot (because if there is one, Postfix doesn't start.

I've also added a bypass if the case in #1572 (starting the updater while no subdomain is set eg. "example.org" instead of "mail.example.org") is met.
The user has to confirm the Message (as seen in the commit) with a link to the issue.

A better way would be to use a Regex for the check, but as seen here https://stackoverflow.com/a/26618995 , may require a much larger codechange.

[dkpost3]

[AlexHuebi]

I've created a VM where a Mailcow instance was set up, but I am not able to recreate that error. Did you change anything that is not in the .gitignore?
And how did you get to this point? Because I had to modify the update.sh in my repository (as seen in the 2nd commit that should be probably removed before merge) so it wont change itself back to the mailcow/mailcow-dockerized repo.

[AlexHuebi]

Note: I've now also modified the part where it says # Silently fixing remote url from andryyy to mailcow and now its asking before changing it back to the default repository

[DerLinkman]

Looks fine to me but need to test it. But don't have time at the moment.

[DerLinkman]

Thank you! Looks good. Just tweaked it a bit to be more colorful and vibrant to notice the users even better.

I also added the DOT Check to the generate_config.sh as it was used their as well (the old version).