Merge pull request #12020 from backstage/rugvip/authnotes

docs: auth & identity doc tweaks to highlight some info more clearly

docs/auth/identity-resolver.md

@@ -12,7 +12,10 @@ If you want to use an auth provider to sign in users, you need to explicitly con
 it have sign-in enabled and also tell it how the external identities should
 be mapped to user identities within Backstage.
 
-## Guest Sign-In Resolver
+## Quick Start
+
+> See [providers](../reference/plugin-auth-backend.providers.md)
+> for a full list of auth providers and their built-in sign-in resolvers.
 
 Backstage projects created with `npx @backstage/create-app` come configured with a
 sign-in resolver for GitHub guest access. This resolver makes all users share

docs/auth/oauth2-proxy/provider.md

@@ -71,4 +71,4 @@ installed in `packages/app/src/App.tsx` like this:
 +    SignInPage: props => <ProxiedSignInPage {...props} provider="oauth2Proxy" />,
 ```
 
-See the [Sign-In with Proxy Providers](../index.md#sign-in-with-proxy-providers) section for more information.
+See [Sign-In with Proxy Providers](../index.md#sign-in-with-proxy-providers) for pointers on how to set up the sign-in page to also work smoothly for local development.