Update src/ty.md

Co-authored-by: Michael Goulet <michael@errs.io>

Author: chenyukang

src/ty.md

@@ -141,7 +141,7 @@ To allocate a new type, you can use the various `new_` methods defined on the [`
 that correspond mostly to the various kinds of types. For example:
 
 ```rust,ignore
-let array_ty = Ty::new_array_with_const_len(tcx, ty,count)
+let array_ty = Ty::new_array_with_const_len(tcx, ty, count)
 ```
 
 These methods all return a `Ty<'tcx>` – note that the lifetime you get back is the lifetime of the