Why todo uses admonition-todo

[hwayne]

Saw the bit at https://github.com/pradyunsg/furo/blob/main/docs/reference/admonitions.md#todo and had to laugh because I've run into the exact same issue! It's because the todo extension manually sets admonition-todo as its node class.

[pradyunsg]

Hehehe.

That's the how it happens. The thing to figure out is why that was done in the code. ;)