Add a fresh contribution doc that includes version and release info

that probably should not be present in the main public documentation

CONTRIBUTING.md

@@ -0,0 +1,35 @@
+# Contributing to `rsconnect-python`
+
+This project aims to uphold Python [community norms](https://www.python.org/psf/conduct/) and make use of [recommended
+tooling](https://packaging.python.org/guides/tool-recommendations/).
+
+## Workflow
+
+The [`test` job in the default GitHub Actions workflow](.github/workflows/main.yml) reflects a typical set of steps for
+building and testing.
+
+## Proposing Change
+
+Any and all proposed changes are expected to be made via [pull
+request](https://help.github.com/en/github/collaborating-with-issues-and-pull-requests/about-pull-requests).
+
+## Versioning and Releasing
+
+All version and release management is done via [annotated git tags](https://git-scm.com/docs/git-tag), as this is the
+repo metadata used by the [`setuptools_scm`](https://github.com/pypa/setuptools_scm) package to generate the version
+string provided as `rsconnect:VERSION` and output by `rsconnect version`.
+
+To create a new release, create and push an annotated git tag:
+
+```bash
+git tag -a 1.2.3 -m 'Release 1.2.3'
+git push origin 1.2.3
+```
+
+Once the tag push is received by GitHub, the relevant workflow action will be triggered and, upon successful completion,
+a release will be created and published to the repository
+[releases](https://github.com/rstudio/rsconnect-python/releases) and the public
+[PYPI](https://pypi.org/project/rsconnect-python/#history).
+
+> **NOTE**: Pre-releases versions must comply with [PIP 440](https://www.python.org/dev/peps/pep-0440/) in order for
+> PIPY to appropriately mark them as pre-releases.