`todo!` documentation should mention optional format arguments

[Marcono1234]

Location

https://doc.rust-lang.org/std/macro.todo.html

Summary

The documentation of the todo! macro currently does not mention at all that it also accepts optional format arguments, for example:

todo!("with {}", 1);

Other macros like unimplemented! at least have the following sentence under "Panics":

Like panic!, this macro has a second form for displaying custom values.

So maybe it would be good to do the following?

• Update the "Panics" section to be similar to https://doc.rust-lang.org/std/macro.unimplemented.html#panics
• Extend / adjust example to also show usage of custom message

[Colonial-Dev]

@rustbot claim

[Colonial-Dev]

Any opinions?

I mostly drew from the docs for unimplemented!, and I also took the liberty of cleaning up some of the formatting/typography.

[Marcono1234]

Thanks! To me this looks good, but I don't know what the maintainers think.