We've added a section to the Directory Opus 13 manual manual to help those upgrading from an older version.
This covers some common questions about installing the update, which may be useful to new users as well.
For people keeping their configs from Opus 12, there's information about how to gain access to new features without having to reset everything.
There's a lot here! You don't need to read it all! We suggest skimming everything, so you're aware of what's there, and then coming back to it as you need things.