diff --git a/README.md b/README.md
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--- a/README.md
+++ b/README.md
@@ -1,3 +1,15 @@
 # runner-images
 
-Image factory for Forgejo action runners
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+Image factory for Forgejo Action runners
+
+## Building
+
+Images can be build locally if needed:
+
+```sh
+python build_image.py <image-name> <Dockerfile path>
+```
+
+CI will also build images when a tag of the format `v*` is pushed. The images built by CI are tagged as `:latest` and pushed to the registry at the run.
+
+If CI workflows are triggered manually (i.e. via `workflow_dispatch`), then the image push is skipped.