Fixed Android Texturecube shader directory

The app was crashing because it was failing to grab the `shaders/texturecubemap/skybox.vert.spv` asset because it was never getting included in the build

android/texturecubemap/example.json

@@ -1,7 +1,7 @@
 {
   "apkname": "vulkanTexturecubemap",
   "directories": {
-    "shaders": "cubemap"
+    "shaders": "texturecubemap"
   },
   "assets": {
     "models": [
@@ -16,4 +16,4 @@
       "cubemap_yokohama_astc_8x8_unorm.ktx"
     ]    
   }
-}
+}