fix test/ui/borrowck/issue-33819

Author: ibraheemdev

src/test/ui/borrowck/issue-33819.rs

@@ -3,7 +3,7 @@ fn main() {
     match op {
         Some(ref v) => { let a = &mut v; },
         //~^ ERROR cannot borrow `v` as mutable, as it is not declared as mutable
-        //~^ HELP try removing `&mut` here
+        //~| HELP try removing `&mut` here
         None => {},
     }
 }