Pause after updating changelog

After updating changelog, Ship.js will pause and give user to check&update the changelog. User can open another terminal or editor to update it. When everything is okay, user can hit enter and Ship.js will continue.

Start by locating the changelog-update step in Ship.js's release flow and reproduce it with a release run. The work is done when Ship.js pauses after updating the changelog, allows the user to inspect or edit it elsewhere, and continues after the user presses Enter.

Written by the indexing model from the issue text.