Surface changelog and workflow releases with badges
Adds top-level badges for the current workflow release version and the
changelog to call attention to these features of the repository more
clearly.
+[![GitHub release (latest by date)](https://img.shields.io/github/v/release/nextstrain/ncov)](https://github.com/nextstrain/ncov/releases)
+[![See recent changes](https://img.shields.io/badge/changelog-See%20recent%20changes-blue)]((https://github.com/nextstrain/ncov/blob/master/docs/change_log.md))
+
# About
This repository analyzes viral genomes using [Nextstrain](https://nextstrain.org) to understand how SARS-CoV-2, the virus that is responsible for the COVID-19 pandemic, evolves and spreads.
