Update release docs.

Author: ghengeveld

docs/contributing/releasing.md

@@ -9,11 +9,12 @@ Release management is currently a manual process, to be performed by core team m
 2. Open a pull request for `release` -> `master`
 3. Write the release notes in the PR description.
 4. Decide on the version number, taking care to follow semver. Do a pre-release before doing the actual release.
-5. Run `yarn bump` to increment the version number and commit it as "Release vX.X.X" (using the correct version number).
-6. Tag the release commit with `git tag vX.X.X` (using the correct version number).
-7. Push the release commit AND tag: `git push --follow-tags`
-8. Publish each package (in `./packages`) to npm using the script below.
-9. Create a new release on GitHub and copy the release notes there.
+5. Run `yarn bump` to increment the version number in all `package.json` files as well as `lerna.json`.
+6. Commit the version change as "Release vX.X.X" (using the correct version number).
+7. Tag the release commit with `git tag vX.X.X` (using the correct version number).
+8. Push the release commit AND tag: `git push --follow-tags`
+9. Publish each package (in `./packages`) to npm using the script below.
+10. Create a new release on GitHub and copy the release notes there.
 
 ```
 yarn build:packages