fix(router): add segmentPath to the link DSL

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

@@ -220,9 +220,14 @@ export class Router {
    * // create /team/33;expand=true/user/11
    * router.createUrlTree(['/team', 33, {expand: true}, 'user', 11]);
    *
-   * // you can collapse static fragments like this
+   * // you can collapse static segments like this (this works only with the first passed-in value):
    * router.createUrlTree(['/team/33/user', userId]);
    *
+   * If the first segment can contain slashes, and you do not want the router to split it, you
+   * can do the following:
+   *
+   * router.createUrlTree([{segmentPath: '/one/two'}]);
+   *
    * // create /team/33/(user/11//aux:chat)
    * router.createUrlTree(['/team', 33, {outlets: {primary: 'user/11', right: 'chat'}}]);
    *