v5.0.0 not marked as a release

[Ryan Hofschneider]

The v5.0.0 tag doesn't have an associated release, so the sidebar on the front page of this repo still reports that v4.2.0 is the latest release.

Just looking at #178 and the Slack announcement, I took a stab at release notes:

A major release incorporating USWDS 2. Check out the migration guide to update your site from earlier uswds-jekyll releases.

Added

• Use Prettier for consistent formatting
• New sidenav-breakpoint key in navigation.yml
• New color configuration keys in theme.yml

Updated

• USWDS to 2.7.0 from USWDS 1.6.9 – and all HTML templates and layouts to match
• Jekyll to 4.0
• Renamed footer type medium to default in footer.yml
• Reorganized _sass directory layout
• Disabled search by default

[Aidan Feldman]

Thanks! Added.