release: add step about making sure 'master' is in sync
release: add step about making sure 'master' is in sync

Otherwise, if we start doing crate releases from the local checkout
(with git tags) and it turns out that origin/master has newer commits,
rebasing local master will then invalidate those tags.

BurntSushi/ripgrep,BurntSushi/ripgrep,BurntSushi/ripgrep,BurntSushi/ripgrep