message: docs(router): clarify that createUrlTree only uses some NavigationExtras
  There is some confusion around which `NavigationExtras` values are used
  by createUrlTree. This specifies that only values that change the URL
  are used. This came up during the discussion in
  PR Close
diff: @@ -867,7 +867,8 @@ export class Router {
  * Otherwise, applies the given command starting from the root.
  *
  * @param commands An array of commands to apply.
  - * @param navigationExtras Options that control the navigation strategy.
  + * @param navigationExtras Options that control the navigation strategy. This function
  + * only utilizes properties in `NavigationExtras` that would change the provided URL.
  * @returns The new URL tree.
  *
  * @usageNotes
  