Update github actions readme file.

The original readme.md file is no longer corresponding
to the current implementation of CI we have, so this is
bringing it more in line with the current state.

Author: Fotis Koutoulakis

.github/workflows/README.md

@@ -1,56 +1,22 @@
-# CBMC packages
-
-This project builds installation packages for the tip of the develop
-branch for MacOS, Windows, and Ubuntu.
-
-There exist installation packages for the latest stable releases of
-CBMC on MacOS and Ubuntu.
-
-On MacOS:
-* brew install cbmc
-
-On Ubuntu:
-* sudo apt-get install software-properties-common
-* sudo add-apt-repository ppa:mt-debian/cbmc-backports
-* sudo apt-get update
-* sudo apt-get install cbmc
-
-This project uses GitHub Actions to build installation packages for
-the tip of the develop branch for MacOS, Windows, and Ubuntu each time
-new commits is added to develop.  The packages reside on GitHub as
-artifacts that can be listed using the GitHub Actions API.
-
-A separate project implements a web page hosted on GitHub Pages that makes
-it easy to find the installation package for the tip of develop.
-
-The stable installation packages describe above for MacOS and Ubuntu
-install into the local operating system's equivalent of
-/usr/local/bin.
-This project builds two kinds of packages:
-* cbmc installs into the equvalent of /usr/local/bin
-* cbmc-latest installs into the equivalent of /usr/local/cbmc-latest/bin,
-  and makes it possible to have two copies of cbmc --- a stable release
-  and a tip of develop --- side-by-side on the same machine.
-
-For each operatin system:
-* The MacOS package is just a tar file of a directory containing the
-  binaries. The directory should be unpacked and placed in the search
-  path. Using Homebrew, "brew install cbmc" will install the latest
-  stable release.  These tar files are intended only to distribute the
-  development versions between stable releases (Homebrew repository
-  updates of the stable versions are quick).
-
-* The Windows package is an Microsoft Installer (msi) for Windows 10
-  with Visual Studio 2019.  It can be installed by double-clicking on the
-  installer or runnin `msexec /i <filename>`.
-
-* The Ubuntu package is a Debian package that can be installed with
-  `dpkg -i <filename>`. There are packages for Ubuntu 18 and Ubuntu 16.
-  These packages are intended to distribute the development versions
-  between stable releases, but also to produce the stable packages uploaded
-  to a Debian or Ubuntu PPA.
-
-The file packages.yaml defines the workflow for GitHub Actions to build the
-packages. Each package is defined by a job that runs in its own
-container. The subdirectories contain files and data needed to build
-each of the packages.
+# CBMC CI infrastructure
+
+This folder contains implementation and configuration files for
+our CI infrastructure on top of Github Actions. Aside from CI,
+it also contains packaging and automated release scripts.
+
+The files in this folder correspond to:
+
+* `build-and-test-Xen.yaml` -> Build Xen using CBMC tools.
+* `csmith.yaml` -> Run 10 randomly generated CSmith tests per Pull Request.
+* `doxygen-check.yaml` -> Build project doxygen documentation per Pull Request.
+* `pull-request-check-cpplint.sh` -> Script that's called per Pull Request to execute
+  `cpplint` over changes.
+* `pull-request-check-clang-format.sh` -> Script that's called per Pull Request
+  to execute `clang-format` over changes.
+* `pull-request-checks.yaml` -> Configuration file for the Github Actions CI jobs
+  for the various platforms.
+* `regular-release.yaml` -> Configuration file for performing an automated release
+  every time a tag of a specific form (`cbmc-x.y.z`) is pushed.
+* `release-packages.yaml` -> Configuration file for performing building of build
+  artifacts that are attached to release when it's being made. Invoked when a
+  regular release is performed.