docs(toh-6): fix tsconfig-aot.json indentation. (#3192)

Author: nhodges

public/docs/_examples/toh-6/ts/tsconfig-aot.json

@@ -20,7 +20,7 @@
   ],
 
   "angularCompilerOptions": {
-   "genDir": "aot",
-   "skipMetadataEmit" : true
- }
+    "genDir": "aot",
+    "skipMetadataEmit" : true
+  }
 }