docs: update branding links (#750)

docs/docs/concepts/authn-vs-authz.mdx

@@ -77,4 +77,4 @@ However, there are some cases where you need to establish 1-1 mappings between u
 
 ### Our customers need custom branding for their sign-in pages
 
-We hear you! The "Organization-level and app-level sign-in experience settings" feature is on [our roadmap](https://logto.productlane.com/roadmap) and will be available soon.
+Please check out [App-specific branding](../recipes/customize-sie/match-your-brand.md#app-specific-branding) and [Organization-specific logos](../recipes/customize-sie/match-your-brand.md#organization-specific-logos) for related configurations.