[xen staging] automation/dockers: add to README how to rebuild all containers

[patchbot@xxxxxxx]

commit 7dc3b362f4ec7a0b47d8c110d82bc657f0a0fdad
Author:     Roger Pau Monne <roger.pau@xxxxxxxxxx>
AuthorDate: Mon Mar 31 18:56:01 2025 +0200
Commit:     Roger Pau Monne <roger.pau@xxxxxxxxxx>
CommitDate: Wed Apr 9 10:42:52 2025 +0200

    automation/dockers: add to README how to rebuild all containers
    
    Document in the README how to rebuild all containers.  This is helpful when
    populating a local docker registry for testing purposes.
    
    Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
---
 automation/build/README.md | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/automation/build/README.md b/automation/build/README.md
index ecc898680c..6c647b1b2a 100644
--- a/automation/build/README.md
+++ b/automation/build/README.md
@@ -108,6 +108,13 @@ env CONTAINER_NO_PULL=1 \
 make -C automation/build opensuse/tumbleweed-x86_64 PUSH=1
 ```
 
+To rebuild all containers the `all` make target can be used, with or without
+the `PUSH` environment variable:
+
+```
+make -C automation/build all PUSH=1
+```
+
 [BuildKit]: https://docs.docker.com/build/buildkit/
 [registry]: https://gitlab.com/xen-project/xen/container_registry
 [registry help]: https://docs.gitlab.com/ee/user/packages/container_registry/
--
generated by git-patchbot for /home/xen/git/xen.git#staging