Update createProp.js

Author: rohit-chouhan

lib/createProp.js

@@ -37,7 +37,7 @@ var createProp = async function createProp(name, description, type, defaultValue
       //===== getter ==========
       var capital = name.charAt(0).toUpperCase() + name.slice(1);
       jsonObj.methods["get" + capital] = {
-        returntype: type,
+        returnType: type,
         description: "Return " + description,
         body: "return this." + name + ";"
       };
@@ -73,4 +73,4 @@ function getJsonFileName() {
   });
 }
 
-exports.createProp = createProp;
+exports.createProp = createProp;