misc: Updated CONTRIBUTING.md with correct deploy steps

Author: kamilogorek

CONTRIBUTING.md

@@ -4,6 +4,8 @@
   * [ ] Consider whether any changes warrant additions to these tests
 * [ ] Stop and think "What version number should this be according to SemVer?"
 * [ ] Add an entry to the [History](https://github.com/getsentry/raven-node/blob/master/History.md) file.
-* [ ] Bump version number in `package.json` using `npm version [patch|minor|major] -m 'release: %s'`.
+* [ ] Bump version number in `package.json`
+* [ ] Commit changes `git commit -am "<version>"`
+* [ ] Create a tag `git tag -a <version> -m "<version>"`
 * [ ] Push to GitHub (`git push origin master --follow-tags`).
 * [ ] Once CI builds pass, `sentry-probot` will publish a release on npm and GitHub.