docs: disambiguate the libraries introduction from the platform

The page title and opening sentence define Akka as "a set of libraries",
which is the entity definition search engines pick up for the product
name as a whole. Name the libraries as the foundation under the platform
and link the SDK and Automated Operations paths from the first paragraph,
so a reader arriving from either kind of search reaches the right page.

Author: TylerJewell

akka-docs/src/main/paradox/typed/guide/introduction.md

@@ -1,6 +1,8 @@
-# Introduction to Akka libraries
+# Introduction to the Akka core libraries
 
-Welcome to Akka, a set of libraries for designing scalable, resilient systems that span processor cores and networks. Akka allows you to focus on meeting business needs instead of writing low-level code to provide reliable behavior, fault tolerance, and high performance.
+The Akka core libraries are the actor, cluster, persistence, and stream foundations underneath the [Akka Agentic AI Platform](https://akka.io/). This page covers the libraries themselves. To build and operate services on the platform, start with the [Akka SDK](https://doc.akka.io/java/index.html) and [Akka Automated Operations](https://doc.akka.io/operations/akka-platform.html).
+
+The libraries let you design scalable, resilient systems that span processor cores and networks. Akka allows you to focus on meeting business needs instead of writing low-level code to provide reliable behavior, fault tolerance, and high performance.
 
 Many common practices and accepted programming models do not address important challenges
 inherent in designing systems for modern computer architectures. To be