tools: create Docker release image, helper build script and requirements

- also create Documentation and issue template

.github/ISSUE_TEMPLATE/release.md

@@ -0,0 +1,19 @@
+---
+name: Release
+about: Issue template to prepare a release step by step.
+title: "Release vX.Y.Z"
+---
+<!-- Make sure to set the proper version in the issue template -->
+Release check-list:
+<!-- Note that some of these steps will be automated in the future -->
+- [ ] Check the release milestone issues, cut out what can't be completed in time
+- [ ] Choose the version number following semantic versioning: https://semver.org/
+- [ ] Checkout the commit for release, create a signed tag with the version name `git tag -s -a -m "vX.Y.Z release" vX.Y.Z`, push it to GitHub with `git push origin refs/tags/vX.Y.Z`
+- [ ] Run sanity checks inside the dev docker: `make pcc` and `make pytest && make coverage`
+- [ ] On the build machine with docker installed, run in your OS terminal in the project dir: `make release_docker`
+- [ ] Re-tag the image with `docker tag concretefhe-release:latest ghcr.io/zama-ai/concretefhe-release:vX.Y.Z`
+- [ ] `docker login ghcr.io`, input your username and GitHub Personal Access Token (PAT). If not already done add `write:packages` to your PAT
+- [ ] Push the release image `docker push ghcr.io/zama-ai/concretefhe-release:vX.Y.Z`
+- [ ] See [here](https://docs.github.com/en/github/administering-a-repository/releasing-projects-on-github/managing-releases-in-a-repository#creating-a-release) to create the release in GitHub using the existing tag, add the pull link \(`ghcr.io/zama-ai/concretefhe-release:vX.Y.Z`\) for the uploaded docker image
+
+All done!