Warn about deprecation.

README.md

@@ -1,16 +1,24 @@
-# A library for reading and writing to Solid pods
+# A library for reading and writing to legacy Solid pods
 
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-The [Solid](https://solid.mit.edu/) project
+The [Solid](https://solidproject.org/) project
 allows people to use apps on the Web
 while storing their data in their own data pod.
 
-`solid-auth-client` is a browser library that allows
-your apps to securely log in to Solid data pods
-and read and write data from them.
+`solid-auth-client` is a legacy browser library
+that allows your apps to log in and read/write data using
+a [Node Solid Server](https://github.com/solid/node-solid-server/).
+
+**⚠️ New projects should use [solid-client-authn](https://github.com/inrupt/solid-client-authn-js) instead,
+which leverages the secure DPoP authentication mechanism
+from the current [Solid specification](https://solid.github.io/authentication-panel/solid-oidc/),
+as implemented by
+the [Community Solid Server](https://github.com/solid/community-server/)
+and
+the [Enterprise Solid Server](https://inrupt.com/products/enterprise-solid-server/).**
 
 ## Usage
 In the browser, the library is accessible through `solid.auth`: