Add DEVELOPMENT.md guide describing release process

Also move the development section from the README.md into the guide, and
expand it with additional information.

DEVELOPMENT.md

@@ -0,0 +1,106 @@
+# Development Guide
+
+## Setting up the dev environment
+
+The package uses the [Hatch](https://hatch.pypa.io) Python project manager. It
+is recommended to [install Hatch](https://hatch.pypa.io/latest/install/#pipx)
+using [pipx](https://pipx.pypa.io/):
+
+```sh
+pipx install hatch
+```
+
+### Installing Python interpreters (optional)
+
+This project aims to be compatible with all the officially-supported versions of
+Python. Check python.org
+[Status of Python versions](https://devguide.python.org/versions/) for more
+info.
+
+To run the tests against all supported Python versions, it is necessary to
+install the relevant distributions of Python. Hatch is able to download these
+Python binaries into the home directory:
+
+```console
+$ hatch python install all
+Installed 3.7 @ /home/develop/.local/share/hatch/pythons/3.7
+Installed 3.8 @ /home/develop/.local/share/hatch/pythons/3.8
+Installed 3.9 @ /home/develop/.local/share/hatch/pythons/3.9
+Installed 3.10 @ /home/develop/.local/share/hatch/pythons/3.10
+Installed 3.11 @ /home/develop/.local/share/hatch/pythons/3.11
+Installed 3.12 @ /home/develop/.local/share/hatch/pythons/3.12
+Installed pypy2.7 @ /home/develop/.local/share/hatch/pythons/pypy2.7
+Installed pypy3.9 @ /home/develop/.local/share/hatch/pythons/pypy3.9
+Installed pypy3.10 @ /home/develop/.local/share/hatch/pythons/pypy3.10
+```
+
+⚠️ Note that Hatch will then modify your shell configuration to add these paths
+to your `$PATH`.
+
+## Building and testing
+
+To launch the tests across all supported Python versions, run:
+
+```sh
+hatch run test:all
+```
+
+To limit the tests to a specific Python version, add a
+[`hatch run`](https://hatch.pypa.io/latest/cli/reference/#hatch-run) `+`
+argument:
+
+```sh
+hatch run +py=3.12 test:all
+```
+
+To lint the code base, use the command:
+
+```sh
+hatch run lint:check
+```
+
+## Updating the contract ABIs
+
+The script `script/update_abi.sh [AUTONITY_COMMIT]` builds the contract ABIs
+using AGC at the specified Git commit ID or tag. Keys are ordered via the `jq`
+tool, in order to produce deterministic output, and the results written to the
+`autonity/abi` directory. Further, it normalizes the commit ID that was used.
+
+After executing the script against a new version of the code, the diffs can be
+reviewed to determine which methods have been modified, removed or added.
+
+## Release checklist for maintainers
+
+Prepare the release (any contributor):
+
+- [ ] _Merge the changes_. All changes must be merged into `master` so that they
+      can have stable commit IDs, which can be referenced from the Changelog.
+- [ ] _Determine the next version number_. Follow the
+      [Semantic Versioning](https://semver.org/) standard to determine the
+      `$NEXT_VERSION` number.
+- [ ] _Prepare the Changelog_. Create a new `CHANGELOG.md` section following
+      [Common Changelog](https://common-changelog.org/). Don't hard wrap lines
+      as it is less readable in plaintext. Remember to add the Github Release
+      link at the bottom.
+
+Make the release (maintainers only):
+
+- [ ] _Bump the version_. Run `hatch version $NEXT_VERSION` to bump the version.
+      Commit the changes with `$NEXT_VERSION` as the commit message.
+- [ ] _Tag the version commit_. Tag this version bump Git commit with the
+      version number: `git tag $NEXT_VERSION master`.
+- [ ] _Push the tag_. As Git tags are not pushed by default, it needs an
+      explicit push: `git push origin $NEXT_VERSION`.
+- [ ] _Build the release artifacts_. Build in a clean environment by recreating
+      it with `hatch env prune`. Then `hatch build --clean`.
+- [ ] _Publish to PyPI_. Push the release artifacts to the
+      [Python Package Index](https://pypi.org/) with `hatch publish`. You will
+      be prompted for credentials. See also the Hatch guide:
+      [How to authenticate for index publishing](https://hatch.pypa.io/latest/how-to/publish/auth/).
+- [ ] _Create the Github Release_.
+      [Create a new Github Release](https://github.com/autonity/autonity.py/releases/new).
+      When completing the form, select the `$NEXT_VERSION` tag, add relevant
+      content from the `CHANGELOG.md` entry, and mark this as the "latest
+      release".
+- [ ] _Announce the release_. Notify relevant chat and social channels about the
+      release. Reach out to community managers to promote it.

README.md

@@ -9,6 +9,8 @@ This package provides typed wrappers around the Autonity-specific extensions of
 Ethereum, using the [Web3.py](https://github.com/ethereum/web3.py) framework,
 for convenient and statically checked interactions with the Autonity network.
 
+This package follows [Semantic Versioning](https://semver.org/).
+
 ## Installation
 
 ```console
@@ -51,28 +53,7 @@ networks.
 
 ## Development
 
-The project uses [hatch](https://hatch.pypa.io/latest/install/#pipx) as the
-build tool. To launch the tests, run:
-
-```console
-hatch run test:all
-```
-
-For linting use the command:
-
-```console
-hatch run lint:check
-```
-
-### Updating the Contract ABIs
-
-The script `script/update_abi.sh [AUTONITY_COMMIT]` builds the contract ABIs
-using AGC at the specified Git commit ID or tag. Keys are ordered via the `jq`
-tool, in order to produce deterministic output, and the results written to the
-`autonity/abi` directory. Further, it normalizes the commit ID that was used.
-
-After executing the script against a new version of the code, the diffs can be
-reviewed to determine which methods have been modified, removed or added.
+Review the [Development Guide](DEVELOPMENT.md).
 
 ## Reporting a Vulnerability