Doc: Make hint clearer (#5988)

-closes https://github.com/assimp/assimp/issues/5981

include/assimp/texture.h

@@ -3,7 +3,7 @@
 Open Asset Import Library (assimp)
 ---------------------------------------------------------------------------
 
-Copyright (c) 2006-2024, assimp team
+Copyright (c) 2006-2025, assimp team
 
 All rights reserved.
 
@@ -169,7 +169,8 @@ struct aiTexture {
     /** Data of the texture.
      *
      * Points to an array of mWidth * mHeight aiTexel's.
-     * The format of the texture data is always ARGB8888 to
+     * The format of the texture data shall always be ARGB8888 if the texture-hint of the type is empty.
+     * If the hint is not empty you can interpret the format by looking into this hint.
      * make the implementation for user of the library as easy
      * as possible. If mHeight = 0 this is a pointer to a memory
      * buffer of size mWidth containing the compressed texture