Merge pull request #1523 from benoit-pierre/pr/update_releases_doc

doc: update documentation about release process

doc/releases.md

@@ -8,10 +8,8 @@ Version numbers:
 
 Steps to cut a new release (from a clean checkout of `master`):
 
-1. Update version in `plover/__init__.py`, and stage the change `git add plover/__init__.py`.
-2. Install towncrier (`pip install towncrier`) and update `NEWS.md`: `towncrier`.
-3. Review the staged changes, check all news fragments in `news.d` were properly handled
-   (merged into `NEWS.md` and removed by towncrier).
-4. Commit: `git commit -m "release $(./setup.py --version)"`
-5. Tag the release: `git tag -m "$(git log -1 --pretty='format:%B')" "v$(./setup.py --version)"`
-6. Push to Github: `git push --follow-tags origin`
+1. Run `tox -e release_prepare {NEW_VERSION_NUMBER}`.
+2. Review the staged changes, check all news fragments in `news.d` were
+   properly handled (merged into `NEWS.md` and removed by towncrier).
+3. Run `tox -e release_finalize`
+4. Follow the last command instructions, and push to GitHub.