add blank material files

bshift/pbr/barney.wad/+~payload/+~payload.mat

@@ -0,0 +1,8 @@
+
+{
+"for" "+0~payload"
+//"basecolor_map" "+0~payload.png"
+//"normal_map" "+0~payload_normal.png"
+//"metal_map" "+0~payload_metal.png"
+//"roughness_map" "+0~payload_roughness.png"
+}