Merge pull request #7 from vdavid/patch-1

Add deprecation notice

Author: burmudar

README.md

@@ -1,5 +1,14 @@
 # Find-replace campaigns (Sourcegraph extension)
 
+## ⚠️ Deprecation notice
+
+**Sourcegraph extensions have been deprecated with the September 2022 Sourcegraph
+release. [Learn more](https://docs.sourcegraph.com/extensions/deprecation).**
+
+The repo and the docs below are kept to support older Sourcegraph versions.
+
+## Description
+
 Create Sourcegraph campaigns that perform a find-replace on multiple files in multiple repositories.
 
 ## What are Sourcegraph campaigns?