test(docs-infra): fix URL for a11y testing of angular.io (#42462)

This commit fixes one of the URLs used for testing the accessibility of
angular.io from `start-routing` to `start/start-routing`. The old URL is
not correct and result in a "Page not found" error.

This commit also increases some of the a11y scores.

PR Close #42462

aio/scripts/test-aio-a11y.js

@@ -23,11 +23,11 @@ const MIN_SCORES_PER_PAGE = {
   '': 100,
   'api': 100,
   'api/core/Directive': 98,
-  'cli': 98,
-  'cli/add': 98,
+  'cli': 100,
+  'cli/add': 100,
   'docs': 100,
   'guide/docs-style-guide': 96,
-  'start-routing': 93,
+  'start/start-routing': 98,
   'tutorial': 98,
 };