Added docs for latest commit

phases/typecheck.mli

@@ -18,6 +18,8 @@
     - The predicate expression of an if, while, or do-while statement must be
       a boolean.
     - Only values of a basic type can be type cast.
+    - Imported array pointers may not be used directly. E.g., [a] in
+      [extern int[n] a] may be used as [a[0]], but not as [foo(a)].
     *)
 
 (** Main phase function, called by {!Main}. *)