ENH make the readme real

Dockerfile_README.md

@@ -0,0 +1,47 @@
+# @@IMAGENAME@@
+[![CI](https://github.com/conda-forge/docker-images/workflows/CI/badge.svg)](https://github.com/conda-forge/docker-images/actions?query=branch%3Amain+workflow%3Aci)
+
+@@SHORTDESCRIPTION@@
+
+## Description
+
+This image is used to power conda-forge's automated package build infrastructure. For more details, see the [conda-forge documentation](https://conda-forge.org/docs/maintainer/infrastructure/) for our infrastructure.
+
+## License
+
+This image is licensed under [BSD-3 Clause](https://github.com/conda-forge/docker-images/blob/main/LICENSE).
+
+## Documentation & Contributing
+
+You can find documentation for how to use the image on the
+upstream [repo](https://github.com/conda-forge/docker-images).
+
+To get in touch with the maintainers of this image, please [make an issue](https://github.com/conda-forge/docker-images/issues/new/choose)
+and bump the `@conda-forge/core` team.
+
+Contributions are welcome in accordance
+with conda-forge's [code of conduct](https://conda-forge.org/community/code-of-conduct/). We accept them through pull requests on the
+upstream [repo](https://github.com/conda-forge/docker-images/compare).
+
+## Important Image Tags
+
+The tags on this image are either:
+
+- latest: used for non-CUDA aware images
+- @@DOCKERTAG@@: the CUDA version used in the image
+
+## Getting Started & Usage
+
+To get started with this image, you can simply run it at the command line with some command:
+
+```bash
+docker run --rm -t condaforge/@@IMAGENAME@@:@@DOCKERTAG@@ echo "hi"
+```
+
+or use it in your Dockerfile:
+
+```Dockerfile
+FROM condaforge/@@IMAGENAME@@:@@DOCKERTAG@@
+```
+
+The image is meant for use in our CI system, but can be used as a base image for other purposes.

scripts/gen_readme

@@ -1,3 +1,15 @@
 #!/bin/bash
 
-cp README.md ${DOCKERFILE:-${DOCKERIMAGE}}/README.md
+readme=${DOCKERFILE:-${DOCKERIMAGE}}/README.md
+cp Dockerfile_README.md $readme
+
+sed -i.bak "s|@@IMAGENAME@@|${DOCKERIMAGE}|g" $readme
+sed -i.bak "s|@@SHORTDESCRIPTION@@|${SHORT_DESCRIPTION}|g" $readme
+sed -i.bak "s|@@DOCKERTAG@@|${DOCKERTAG}|g" $readme
+
+echo "========================================================="
+echo "========================================================="
+echo "generated README.md"
+cat $readme
+echo "========================================================="
+echo "========================================================="