Update README.md to delete old links (#1372)

Author: pamelafox

README.md

@@ -35,11 +35,6 @@ urlFragment: azure-search-openai-demo
   - [Deploying](#deploying)
   - [Deploying again](#deploying-again)
 - [Sharing environments](#sharing-environments)
-- [Enabling optional features](#enabling-optional-features)
-  - [Enabling Integrated Vectorization](#enabling-integrated-vectorization)
-  - [Enabling authentication](#enabling-authentication)
-  - [Enabling login and document level access control](#enabling-login-and-document-level-access-control)
-  - [Enabling CORS for an alternate frontend](#enabling-cors-for-an-alternate-frontend)
 - [Using the app](#using-the-app)
 - [Running locally](#running-locally)
 - [Monitoring with Application Insights](#monitoring-with-application-insights)