Cleanup markdown sample code (#19)

* Use const/let in sample code

* run eslint on markdown code

* run eslint on markdown code

Author: Christopher Baker

CONTRIBUTING.md

@@ -78,12 +78,13 @@ To output minified versions, in the `build.js` add `minify: true` to the outputs
 
 ```js
 {
-  // in build.js export config
-  outputs: {
-    "+cjs": { minify: true },
-    "+amd": { minify: true },
-    "+global-js": { minify: true }
-  }
+
+	// in build.js export config
+	outputs: {
+		"+cjs": { minify: true },
+		"+amd": { minify: true },
+		"+global-js": { minify: true }
+	}
 }
 ```