Switch to using code anchors (pun!) for code snippets from the tic-tac-toe program. This way the code in the book remains in sync without having to keep duplicating code into the book.
There were 2-3 snippets, I did not convert since they showed gradual changes before getting to the final version.
It all looks good in my local mdbook but please have a look.
PS. I may have run Prettier over the ts test file. Forgive me!
It's the same as https://github.com/coral-xyz/anchor-book/pull/81. I just had to change the source branch so new PR...