Restore unreleased section of changelog for next version

Author: takluyver

docs/changelog.md

@@ -5,6 +5,24 @@
 
 # Changelog
 
+## [Unreleased]
+
+!!! note
+    All of the changes here are deployed to our current environment, even though
+    a release hasn't been made for them yet. If you want to have these updates
+    in a personal environment you'll need to install the package from git.
+
+    ```bash title="Installation command"
+    pip install git+https://github.com/European-XFEL/EXtra.git
+    ```
+
+Added:
+
+Fixed:
+
+Changed:
+
+
 ## [2026.1]
 
 Added in components: