finished last C file

TODO.md

@@ -47,7 +47,7 @@
 - [x] **`wildcow`**
   - [~] Test and explain `update()` and `gotoxy()`.
   - [x] Create an animated cow using `update()`, `gotoxy()`, and `sleep()`.
-- [ ] **`reading_cow`**
+- [x] **`reading_cow`**
   - [x] Cow "reads" a file character by character, displaying each in its mouth before "swallowing".
 
 ---