Rewrite README in markdown (#6)

Author: francium

README.md

@@ -0,0 +1,68 @@
+# Maybe
+
+[![GitHub Workflow Status (branch)](https://img.shields.io/github/actions/workflow/status/rustedpy/maybe/ci.yml?branch=master)](https://github.com/rustedpy/maybe/actions/workflows/ci.yml?query=branch%3Amaster)
+[![Coverage](https://codecov.io/gh/rustedpy/maybe/branch/master/graph/badge.svg)](https://codecov.io/gh/rustedpy/maybe)
+
+A simple Maybe (Option) type for Python 3 [inspired by Rust](
+https://doc.rust-lang.org/std/option/), fully type annotated.
+
+## Installation
+
+Latest release:
+
+```sh
+$ pip install rustedpy-maybe
+```
+
+
+Latest GitHub `master` branch version:
+
+```sh
+$ pip install git+https://github.com/rustedpy/maybe
+```
+
+## Summary
+
+**Experimental. API subject to change.**
+
+The idea is that a possible value can be either `Some(value)` or `Nothing()`,
+with a way to differentiate between the two. `Some` and `Nothing` are both
+classes encapsulating a possible value.
+
+Example usage,
+
+```python
+from maybe import Nothing, Some
+
+o = Some('yay')
+n = Nothing()
+assert o.unwrap_or_else(str.upper) == 'yay'
+assert n.unwrap_or_else(lambda: 'default') == 'default'
+```
+
+## Contributing
+
+These steps should work on any Unix-based system (Linux, macOS, etc) with Python
+and `make` installed. On Windows, you will need to refer to the Python
+documentation (linked below) and reference the `Makefile` for commands to run
+from the non-unix shell you're using on Windows.
+
+1. Setup and activate a virtual environment. See [Python docs][pydocs-venv] for more
+   information about virtual environments and setup.
+2. Run `make install` to install dependencies
+3. Switch to a new git branch and make your changes
+4. Test your changes:
+  - `make test`
+  - `make lint`
+  - You can also start a Python REPL and import `maybe`
+5. Update documentation
+  - Edit any relevant docstrings, markdown files
+  - Run `make docs`
+6. Add an entry to the [changelog](./CHANGELOG.md)
+5. Git commit all your changes and create a new PR.
+
+[pydocs-venv]: https://docs.python.org/3/library/venv.html
+
+## License
+
+MIT License

README.rst

@@ -2,7 +2,7 @@
 name = rustedpy-maybe
 version = attr: maybe.__version__
 description = A Rust-like option type for Python
-long_description = file: README.rst
+long_description = file: README.md
 keywords = rust, option, maybe, enum
 author = francium
 author_email = [email protected]