mention pbrSpecularGlossiness support

code/glTF2Asset.h

@@ -44,6 +44,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  * glTF Extensions Support:
  *   KHR_binary_glTF: full
+ *   KHR_materials_pbrSpecularGlossiness full
  */
 #ifndef GLTF2ASSET_H_INC
 #define GLTF2ASSET_H_INC