Use callouts like so: https://crates.io/crates/mdbook-callouts
You will need to have rust and run cargo install mdbookand cargo install mdbook-callouts
if you don't have the packages already.
To build, open the book and have it auto-update on save, do mdbook serve --open.
Alternatively, you can also use mdbook build --open.
Make sure you are NOT merging directly into master!! make a branch with ur name and day in it and do a pull request :)