Added hcl to json example for nested objects (#36)

It was unclear how nested object example in hcl would map to json.
README now updated to include an example of the son equivalent
to a hcl nested object.

README.md

@@ -103,6 +103,16 @@ variable "ami" {
     description = "the AMI to use"
 }
 ```
+This would be equivalent to the following json:
+``` json
+{
+  "variable": {
+      "ami": {
+          "description": "the AMI to use"
+        }
+    }
+}
+```
 
 ## Thanks