docs: merge redundant authentication points in readme

Consolidates the two separate "Key Capabilities" points related to
authentication into a single, more concise entry.

This improves readability and removes redundancy while still effectively
highlighting the full scope of the authentication system, including both
standard user flows and the secure dashboard login.

Author: fulleni

README.md

@@ -16,10 +16,10 @@ management dashboard](https://github.com/headlines-toolkit/ht-dashboard).
 
 ## ✨ Key Capabilities
 
-*   🔒 **Effortless User Authentication:** Provide secure and seamless user access
-    with flexible flows including passwordless sign-in, anonymous access, and
-    the ability to easily link anonymous accounts to permanent ones. Focus on
-    user experience while `ht_api` handles the security complexities.
+*   🔒 **Flexible & Secure Authentication:** Provide seamless user access with
+    a unified system supporting passwordless sign-in, anonymous guest
+    accounts, and a secure, context-aware login flow for privileged dashboard
+    users (e.g., 'admin', 'publisher').
 
 *   ⚡️ **Flexible Role-Based Access Control (RBAC):** Implement granular
     permissions with a flexible, multi-role system. Assign multiple roles to