Add new workflows

.github/workflows/README.md

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+# How do the workflows work?
+
+1. When there is a push to the private repo's 'dev' branch (private/dev),
+`regress` workflow runs the regression tests.
+
+1. If `regress` workflow fails on 'private/dev', `sync` workflow gets triggered
+and it pushes the latest changes to the public repo's 'dev' branch (public/dev).
+After this push, `regress` workflow will also run on 'public/dev'.
+
+1. If `regress` workflow successfully passes on 'private/dev', `version`
+workflow gets triggered. It creates a new version commit and tag, and pushes to
+'private/dev', 'public/dev', 'public/stable'.
+
+1. When there is a push with new version to the 'public/stable' branch, `deploy`
+workflow runs. It deploys the PyPI package of OpenRAM.
+
+1. If there is a pull request on either repo, `regress` workflow runs on that
+pull request.
+
+1. If there is a push to 'public/dev', `regress` workflow runs (it also happens
+when pull requests are merged).
+
+1. If `regress` workflow successfully passes on 'public/dev', `version`
+workflow gets triggered. It creates a new version commit and tag, and pushes to
+'private/dev', 'public/dev', and 'public/stable'.
+
+
+
+## Important Notes
+
+1. Workflows understand that the latest commit has a new version with the
+following commit message syntax.
+
+    ```
+    Bump version: <any message>
+    ```
+
+    Automatically generated version commit have the following syntax:
+
+    ```
+    Bump version: a.b.c -> a.b.d
+    ```
+
+1. `version` workflow only increments the right-most version digit. Other digits
+in the version number must be updated manually following the syntax above.
+
+1. `regress` workflow doesn't run if the push has a new version. We assume that
+this commit was automatically generated after a previous commit passed `regress`
+workflow or was manually generated with caution.
+
+1. `regress` workflow doesn't run on branches named 'stable'.
+
+1. `deploy` workflow only runs on branches named 'stable'.
+
+1. `version` workflow is only triggered from branches named 'dev' if they pass
+`regress` workflow.
+
+1. `sync` workflow only runs on the private repo.
+
+1. Pull requests merged on to 'public/dev' will also trigger `regress` and it
+can create a new version.
+
+1. Merging pull requests that don't pass `regress` workflow on the public repo
+should be avoided since it won't update the private repo automatically. To
+prevent merging by mistake, the dev branch can be protected in the GitHub
+settings.
+
+1. Merging pull requests on the private repo should be safe in any case.
+