Add linux installation informations

[pprw]

Thanks for taking this wonderful software to a next level.

This is just a quick issue to suggest adding links to snap and flatpak packages. The installation for linux is not detailed and one could think compilation is the only way.

https://snapcraft.io/scantailor-advanced
https://flathub.org/apps/details/com.github._4lex4.ScanTailor-Advanced

[leonleon33156]

这是来自QQ邮箱的假期自动回复邮件。您好，我最近正在休假中，无法亲自回复您的邮件。我将在假期结束后，尽快给您回复。