Fix "too" -> "foo" typo in format.rs

clippy_lints/src/format.rs

@@ -21,7 +21,7 @@ use crate::rustc_errors::Applicability;
 /// **What it does:** Checks for the use of `format!("string literal with no
 /// argument")` and `format!("{}", foo)` where `foo` is a string.
 ///
-/// **Why is this bad?** There is no point of doing that. `format!("too")` can
+/// **Why is this bad?** There is no point of doing that. `format!("foo")` can
 /// be replaced by `"foo".to_owned()` if you really need a `String`. The even
 /// worse `&format!("foo")` is often encountered in the wild. `format!("{}",
 /// foo)` can be replaced by `foo.clone()` if `foo: String` or `foo.to_owned()`