Document how to scale manually.
diff --git a/include/freetype/freetype.h b/include/freetype/freetype.h
index 7301863..34ad48a 100644
--- a/include/freetype/freetype.h
+++ b/include/freetype/freetype.h
@@ -1530,7 +1530,13 @@ FT_BEGIN_HEADER
/* values of the corresponding fields in @FT_FaceRec. Some values */
/* like ascender or descender are rounded for historical reasons; */
/* more precise values (for outline fonts) can be derived by scaling */
- /* the corresponding @FT_FaceRec values manually. */
+ /* the corresponding @FT_FaceRec values manually, with code similar */
+ /* to the following. */
+ /* */
+ /* { */
+ /* scaled_ascender = FT_MulFix( face->root.ascender, */
+ /* size_metrics->y_scale ); */
+ /* } */
/* */
/* Note that due to glyph hinting and the selected rendering mode */
/* these values are usually not exact; consequently, they must be */