Here's how I got this to work.

First, get a list of all the build labels:

cm find labels "where name like 'build-%'" --format="{name}"

which will return something like:

build-25.11.24.02
build-25.11.24.01
build-25.11.25.01
build-25.11.26.01
build-25.11.26.02

go through that list and grab the two most recent tags. Then run the folowing two commands to get the changesetid's:

cm find labels "where name='build-25.11.26.01' or name='build-25.11.26.02'" --format="{changeset}" --nototal

which will return:

2662
2668

then you can run:

cm find changeset "where changesetid > 2662 and changesetid <= 2668" --format="- {comment}" --nototal

This will return the changeset notes which can be formatted however. The --format option that I used above creates a markdown list.