Update the comment on lower_expr_try

I'd updated the ones inside the method, but not its doc comment.

Author: scottmcm

compiler/rustc_ast_lowering/src/expr.rs

@@ -1559,13 +1559,14 @@ impl<'hir> LoweringContext<'_, 'hir> {
 
     /// Desugar `ExprKind::Try` from: `<expr>?` into:
     /// ```rust
-    /// match Try::into_result(<expr>) {
-    ///     Ok(val) => #[allow(unreachable_code)] val,
-    ///     Err(err) => #[allow(unreachable_code)]
-    ///                 // If there is an enclosing `try {...}`:
-    ///                 break 'catch_target Try::from_error(From::from(err)),
-    ///                 // Otherwise:
-    ///                 return Try::from_error(From::from(err)),
+    /// match Try::branch(<expr>) {
+    ///     ControlFlow::Continue(val) => #[allow(unreachable_code)] val,,
+    ///     ControlFlow::Break(residual) =>
+    ///         #[allow(unreachable_code)]
+    ///         // If there is an enclosing `try {...}`:
+    ///         break 'catch_target Try::from_residual(residual),
+    ///         // Otherwise:
+    ///         return Try::from_residual(residual),
     /// }
     /// ```
     fn lower_expr_try(&mut self, span: Span, sub_expr: &Expr) -> hir::ExprKind<'hir> {