Another minor documentation improvement.

include/freetype/ftcolor.h

@@ -125,9 +125,9 @@ FT_BEGIN_HEADER
    *     The number of palettes.
    *
    *   palette_name_ids ::
-   *     A read-only array of palette name IDs with `num_palettes` elements,
-   *     corresponding to entries like 'dark' or 'light' in the font's 'name'
-   *     table.
+   *     An optional read-only array of palette name IDs with `num_palettes`
+   *     elements, corresponding to entries like 'dark' or 'light' in the
+   *     font's 'name' table.
    *
    *     An empty name ID in the 'CPAL' table gets represented as value
    *     0xFFFF.
@@ -135,8 +135,8 @@ FT_BEGIN_HEADER
    *     `NULL` if the font's 'CPAL' table doesn't contain appropriate data.
    *
    *   palette_flags ::
-   *     A read-only array of palette flags with `num_palettes` elements.
-   *     Possible values are an ORed combination of
+   *     An optional read-only array of palette flags with `num_palettes`
+   *     elements.  Possible values are an ORed combination of
    *     @FT_PALETTE_FOR_LIGHT_BACKGROUND and
    *     @FT_PALETTE_FOR_DARK_BACKGROUND.
    *
@@ -147,7 +147,7 @@ FT_BEGIN_HEADER
    *     same size.
    *
    *   palette_entry_name_ids ::
-   *     A read-only array of palette entry name IDs with
+   *     An optional read-only array of palette entry name IDs with
    *     `num_palette_entries`.  In each palette, entries with the same index
    *     have the same function.  For example, index~0 might correspond to
    *     string 'outline' in the font's 'name' table to indicate that this