docs: branding fixes (#14132)

Angular 1.x -> AngularJS
Angular 1 -> AngularJS
Angular1 -> AngularJS
Angular 2+ -> Angular
Angular 2.0 -> Angular
Angular2 -> Angular

I have deliberately not touched any of the symbol names as that would cause big merge collisions with Tobias's work.

All the renames are in .md, .json, and inline comments and jsdocs.

PR Close #14132

modules/@angular/router/src/router.ts

@@ -326,7 +326,7 @@ export class Router {
   navigated: boolean = false;
 
   /**
-   * Extracts and merges URLs. Used for Angular 1 to Angular 2 migrations.
+   * Extracts and merges URLs. Used for AngularJS to Angular migrations.
    */
   urlHandlingStrategy: UrlHandlingStrategy = new DefaultUrlHandlingStrategy();
 

modules/@angular/router/src/router_module.ts

@@ -110,7 +110,7 @@ export function routerNgProbeToken() {
  * In addition, we often want to split applications into multiple bundles and load them on demand.
  * Doing this transparently is not trivial.
  *
- * The Angular 2 router solves these problems. Using the router, you can declaratively specify
+ * The Angular router solves these problems. Using the router, you can declaratively specify
  * application states, manage state transitions while taking care of the URL, and load bundles on
  * demand.
  *

modules/@angular/router/src/url_handling_strategy.ts

@@ -9,7 +9,7 @@
 import {UrlTree} from './url_tree';
 
 /**
- * @whatItDoes Provides a way to migrate Angular 1 applications to Angular 2.
+ * @whatItDoes Provides a way to migrate AngularJS applications to Angular.
  *
  * @experimental
  */