[truetype] Improve comment.
diff --git a/src/truetype/ttinterp.c b/src/truetype/ttinterp.c
index 80c38ad..dcbb9f0 100644
--- a/src/truetype/ttinterp.c
+++ b/src/truetype/ttinterp.c
@@ -5767,7 +5767,7 @@
/* */
/* UNDOCUMENTED: According to Greg Hitchcock, there is one (virtual) */
/* contour in the twilight zone, namely contour number */
- /* zero. */
+ /* zero which includes all points of it. */
/* */
static void
Ins_SHC( INS_ARG )