Reference `fopen` in the docs.
diff --git a/include/freetype/freetype.h b/include/freetype/freetype.h
index 43eb90f..ad9610d 100644
--- a/include/freetype/freetype.h
+++ b/include/freetype/freetype.h
@@ -2186,6 +2186,10 @@ FT_BEGIN_HEADER
* FreeType error code. 0~means success.
*
* @note:
+ * The `pathname` string should be reconizable as such by a standard
+ * `fopen()` call on your system. If that is not sufficient to address
+ * all file name possiblities, you can use @FT_Open_Face.
+ *
* Use @FT_Done_Face to destroy the created @FT_Face object (along with
* its slot and sizes).
*/