Upgrade from 1.7.8 to 1.8

Not sure if there is an actual guide for the upgrading / migration of 1.7.x to 1.8, but can someone kindly point me to the pinned post for the relevant guide for the upgrading?

Another question is, may I check if 1.8 is a stable release currently? (sorry I have not been here for quite some time)

Thank you very much for your responses.

Everything you need to know is the in release notes: http://xibo.org.uk/manual-tempel/en/release_notes_1.8.1.html, which is the current stable release.

There were big changes between 1.7 and 1.8 - these are better explained in the 1.8.0 release notes.