Rollup merge of rust-lang#89781 - Wilfred:patch-2, r=JohnTitor

Add missing words in `Infallible` docs

This sentence was previously incomplete.

Author: the8472

library/core/src/convert/mod.rs

@@ -664,7 +664,7 @@ impl AsMut<str> for str {
 ///
 /// However there is one case where `!` syntax can be used
 /// before `!` is stabilized as a full-fledged type: in the position of a function’s return type.
-/// Specifically, it is possible implementations for two different function pointer types:
+/// Specifically, it is possible to have implementations for two different function pointer types:
 ///
 /// ```
 /// trait MyTrait {}