Rollup merge of rust-lang#89777 - pierwill:fix-88233, r=Mark-Simulacrum

Edit explanation of test for nested type ascriptions

Fixes typo ("an ascribing") and removes extra.

Closes rust-lang#88233.

src/test/ui/pattern/bindings-after-at/nested-type-ascription-syntactically-invalid.rs

@@ -1,5 +1,5 @@
 // Here we check that type ascription is syntactically invalid when
-// not in the top position of a ascribing a let binding or function parameter.
+// not in the top position of an ascribing `let` binding or function parameter.
 
 
 // This has no effect.