LumiCode changes often, and it keeps its own release notes, so the quickest way to see what's new is to ask LumiCode itself. It tells you when a newer version has something for you, shows you exactly what that is, and updates in one command.
Finding out what's new
Once a day, in an interactive session, LumiCode checks whether a newer version is available. When the newer version has release notes yours doesn't, the banner says how many, for example 3 new.
Type /whats-new to read them. LumiCode lists the changes the newer version would bring, newest first, then offers to update. If no check has run yet in this session, /whats-new checks straight away; otherwise it shows what the last check found, and when.
To stop the daily check, run /set update-check off. /whats-new and /update still work whenever you use them.
Seeing every change
/whats-new all prints every release note, newest first, without offering to update. It's a good way to catch up straight after you install LumiCode.
Each note is dated rather than numbered, because the dates are what tell you which changes you have.
Updating
Type /update. LumiCode downloads the newest version and installs it. Restart lumi afterwards to use it.
On Windows, LumiCode can't replace itself while it's running. Instead, /update downloads the new version and shows you the command to run after you exit.