Rollup merge of rust-lang#76403 - scileo:doc-all-impls, r=lcnr

Fix documentation for TyCtxt::all_impls

`TyCtxt::all_impls` documentation was wrong about the return type.

compiler/rustc_middle/src/ty/trait_def.rs

@@ -167,7 +167,7 @@ impl<'tcx> TyCtxt<'tcx> {
         }
     }
 
-    /// Returns a vector containing all impls
+    /// Returns an iterator containing all impls
     pub fn all_impls(self, def_id: DefId) -> impl Iterator<Item = DefId> + 'tcx {
         let TraitImpls { blanket_impls, non_blanket_impls } = self.trait_impls_of(def_id);