Update README.md with archive notice (#12970)

* Update README.md with archive notice

* lint

Author: langleyd

README.md

@@ -10,22 +10,18 @@
 
 # matrix-react-sdk
 
-This is a react-based SDK for inserting a Matrix chat/voip client into a web page.
-
-This package provides the React components needed to build a Matrix web client
-using React. It is not useable in isolation, and instead must be used from
-a 'skin'. A skin provides:
-
--   Customised implementations of presentation components.
--   Custom CSS
--   The containing application
--   Zero or more 'modules' containing non-UI functionality
-
-As of Aug 2018, the only skin that exists is
-[`vector-im/element-web`](https://github.com/vector-im/element-web/); it and
-`matrix-org/matrix-react-sdk` should effectively
-be considered as a single project (for instance, matrix-react-sdk bugs
-are currently filed against vector-im/element-web rather than this project).
+## matrix-react-sdk is now actively maintained at [element-hq/matrix-react-sdk](https://github.com/element-hq/matrix-react-sdk)
+
+This is a react-based SDK for inserting a Matrix chat/voip client into a web page developed from 2015 through 2024 as part of the Matrix.org Foundation.
+
+This package provides the React components needed to build a Matrix web client using React. It is not usable in isolation, and instead must be used from a 'skin'.
+
+The only skin that existed during its development was [ vector-im/element-web](https://github.com/element-hq/element-web); it and `matrix-org/matrix-react-sdk` have effectively been considered as a single project (for instance, matrix-react-sdk bugs have been filed against vector-im/element-web rather than this project). For this reason it is now maintained at [element-hq/matrix-react-sdk](https://github.com/element-hq/matrix-react-sdk).
+
+See the following blog posts for more information:
+
+-   https://matrix.org/blog/2024/08/heart-of-matrix/
+-   https://element.io/blog/sustainable-licensing-at-element-with-agpl/
 
 ## Developer Guide