Update Security reference landing page (#1901)

Updates the Security Ref landing page.

Author: jmikell821

reference/security/index.md

@@ -11,7 +11,7 @@ This section contains reference information for {{elastic-sec}} features, includ
 
 * [Fields and object schemas](/reference/security/fields-and-object-schemas/index.md)
 * [Endpoint command reference](/reference/security/endpoint-command-reference.md)
-* [Detection Rules Overview](detection-rules://index.md)
+* [Prebuilt detection rules reference](detection-rules://index.md)
 
 To learn more about Security features and how to get started, refer to [{{elastic-sec}}](/solutions/security.md).
 To interface with {{elastic-sec}} features, you can use these [APIs](/solutions/security/apis.md).