Update RELEASING documentation

RELEASING

@@ -5,15 +5,10 @@ Release Checklist
 [ ] Update the metadata in zonefile_metadata.json to include the latest tzdata
     release from https://www.iana.org/time-zones.
 [ ] If necessary, update the tzdata mirror at https://github.com/dateutil/tzdata
-[ ] Update NEWS with list of changes, giving credit to contributors.
-[ ] Build the source distribution as, at a minimum, .tar.gz and .zip
-[ ] Verify that the source distribution contains all necessary components.
-[ ] Build the binary distribution as a wheel
-[ ] Verify that the binary distribution can be installed and works.
-[ ] Generate MD5 hashes for the source and binary distributions
-[ ] Sign the source and binary distributions with a GPG key (if not the one
-    that made the release, then one signed by the one that made the last
-    release)
+[ ] Update NEWS with list of changes:
+    [ ] Invoke `tox -e towncrier -- --version <NEXT_VERSION>`
+    [ ] Make sure that only `template.rst` remains in changelog.d/
+    [ ] Manually clean up the new NEWS file and then check it in.
 [ ] Commit the changes in git and make a pull request.
 [ ] Accept the pull request and tag the repository with the release number.
 [ ] Add the contents of the NEWS file to the github release notes for the
@@ -35,4 +30,34 @@ for more details.
 
 Versioning
 ----------
-Try and keep to a semantic versioning scheme (http://semver.org/).
+Try and keep to a semantic versioning scheme (http://semver.org/). The versions
+are managed with setuptools_scm, so to update the version, simply tag the
+relevant commit with the new version number.
+
+
+Building and Releasing
+----------------------
+Building and releasing can be done using the `release.py` script, which
+automates building, signing and uploading. Since it uses GPG for signing and
+for decrypting a stored token, it requires that `gpg` be installed on your
+system. Because it has python dependencies, the best way to use the
+`release.py` script is to invoke it using `tox`. To build the source and binary
+distributions, use:
+
+    tox -e build
+
+This will build and sign the distributions and put them in `dist/`. Once that
+is done, you can release them with:
+
+    tox -e release
+
+If you have the token stored in your `~/.pypirc` file. If you have stored the
+relevant token in an encrypted file, use the `--passfile` argument:
+
+    tox -e release -- --passfile token.gpg
+
+The `release` command defaults to uploading to test.pypi.org. To upload to
+pypi.org, use the `--release` flag, so putting it all together, we have:
+
+    tox -e build
+    tox -e release -- --passfile token.gpg --release