Fix typo in todo! macro docstring

Author: kormosi

library/core/src/macros/mod.rs

@@ -713,7 +713,7 @@ macro_rules! unimplemented {
 /// Indicates unfinished code.
 ///
 /// This can be useful if you are prototyping and are just looking to have your
-/// code typecheck.
+/// code typechecked.
 ///
 /// The difference between [`unimplemented!`] and `todo!` is that while `todo!` conveys
 /// an intent of implementing the functionality later and the message is "not yet