BaseService terminology: Rename url to route (#2278)

The term “url” is overloaded in services, to refer to the Shields route and also the API URL. Calling the Shields URL a “route” is on the whole more descriptive, and makes it clearer and more obvious which one of these we’re talking about. It’s a small thing, though seems like an improvement.

We have a few functions called `buildUrl`. I’ve renamed them to `buildRoute` when they refer to routes, and left them as `buildUrl` when they refer to API URLs.

I included a minor style tweak and some formatting cleanup in `TUTORIAL.md`.

services/node/node.service.js

@@ -12,8 +12,8 @@ module.exports = class NodeVersion extends NPMBase {
     return { label: 'node' }
   }
 
-  static get url() {
-    return this.buildUrl('node/v', { withTag: true })
+  static get route() {
+    return this.buildRoute('node/v', { withTag: true })
   }
 
   static get examples() {