Updated BUILDING.md

BUILDING.md

@@ -2,6 +2,13 @@
 
 The containers are built using GitHub Actions. The workflow is defined in [`.github/workflows/apptainer-image.yml`](.github/workflows/apptainer-image.yml).
 
-The workflow is triggered on every push with the tag `sif-<containername>`. It builds the named container and pushes it to the GitHub Container Registry.
+The workflow is triggered on every push with the tag `sif-<containername>-v*`. It builds the named container and pushes it to the GitHub Container Registry.
 
-Before containers that depend on other containers can be built, the dependent containers must be built and pushed to the registry. So, if `ubuntu22.04_turbovnc` depends on `ubuntu22.04_interactive`, you must first push a commit with the tag `sif-ubuntu22.04_interactive` for it to be built. Then, you can push a commit with the tag `sif-ubuntu22.04_turbovnc`.
+Before containers that depend on other containers can be built, the dependent containers must be built and pushed to the registry. So, if `ubuntu22.04_turbovnc` depends on `ubuntu22.04_interactive`, you must first push a commit with the tag `sif-ubuntu22.04_interactive-v1.2345` for it to be built. Then, you can push a commit with the tag `sif-ubuntu22.04_turbovnc-v1.2345`.
+
+The easiest way to do this is:
+
+```bash
+git tag -f sif-ubuntu22.04_turbovnc-v0.0.1 # -f to overwrite the tag if it already exists
+git push -f origin sif-ubuntu22.04_turbovnc-v0.0.1 # -f to overwrite the tag if it already exists
+```