Merge pull request #692 from humanmade/issue-1950-update-documentation

Adds breaking changes section

Author: mikelittle

other-docs/guides/upgrading/v26.md

@@ -63,6 +63,12 @@ For more details check the [WordPress 6.9 Field Guide](https://make.wordpress.or
 - **Traefik** has been upgraded to **v3**, improving local server stability and ensuring compatibility with the latest versions of **Docker** and **Docker Desktop**. If you have added **custom Docker containers** to your local stack, you’ll need to update any **Traefik labels/annotations** in your add-ons to be compatible with Traefik v3. Refer to the Docker provider documentation for updated label formats and options of [Traefik for Docker](https://doc.traefik.io/traefik/providers/docker/)
 - **MySQL** has been upgraded to **v8.0.44** which is a maintenance release focused on fixes and incremental performance improvements, including updates across **InnoDB stability**, **query/optimizer correctness**, and **bundled OpenSSL refreshes on supported platforms**.
 
+### Breaking changes
+
+- We upgraded our Enhanced Search module to use ElasticPress v5, which removed support for indexing users and user metadata. If you 
+  were using this feature, you can add the 10Up plugin [ElasticPress Labs](https://github.com/10up/ElasticPressLabs) to 
+  re-enable user indexing.
+
 ### Altis Core improvements
 
 We have incorporated many updates to modules and libraries in Altis to bring in important bug fixes and improvements.