docs: add redirect from angular.io/guide to angular.io/docs (angular#43341)

PR Close angular#43341

Author: David Shevitz

aio/firebase.json

@@ -61,6 +61,7 @@
       {"type": 301, "source": "/docs/*/latest/guide/server-communication.html", "destination": "/guide/http"},
       {"type": 301, "source": "/docs/*/latest/guide/style-guide.html", "destination": "/guide/styleguide"},
       {"type": 301, "source": "/guide/bazel", "destination": "https://github.com/angular/angular/blob/master/packages/bazel/docs/BAZEL_SCHEMATICS.md"},
+      {"type": 301, "source": "/guide", "destination": "/docs"},
       {"type": 301, "source": "/guide/cli-quickstart", "destination": "/start"},
       {"type": 301, "source": "/guide/i18n", "destination": "/guide/i18n-overview"},
       {"type": 301, "source": "/guide/service-worker-getstart", "destination": "/guide/service-worker-getting-started"},

aio/tests/deployment/shared/URLS_TO_REDIRECT.txt

@@ -203,6 +203,7 @@
 /guide/cli-quickstart --> /start
 /guide/displaying-data --> /start#template-syntax
 /guide/i18n --> /guide/i18n-overview
+/guide --> /docs
 /guide/learning-angular --> /start
 /guide/learning-angular.html --> /start
 /guide/metadata --> /guide/aot-compiler