chore: Update README CI badge. (#106)

README.md

@@ -1,6 +1,6 @@
 # LaunchDarkly Javascript SDK Core Components
 
-[![Circle CI](https://circleci.com/gh/launchdarkly/js-sdk-common/tree/master.svg?style=svg)](https://circleci.com/gh/launchdarkly/js-sdk-common/tree/master)
+[![Actions Status][ci-badge]][ci]
 
 ## LaunchDarkly overview
 
@@ -33,3 +33,6 @@ We encourage pull requests and other contributions from the community. Check out
     * [docs.launchdarkly.com](https://docs.launchdarkly.com/  "LaunchDarkly Documentation") for our documentation and SDK reference guides
     * [apidocs.launchdarkly.com](https://apidocs.launchdarkly.com/  "LaunchDarkly API Documentation") for our API documentation
     * [blog.launchdarkly.com](https://blog.launchdarkly.com/  "LaunchDarkly Blog Documentation") for the latest product updates
+
+[ci-badge]: https://github.com/launchdarkly/js-sdk-common/actions/workflows/ci.yml/badge.svg
+[ci]: https://github.com/launchdarkly/js-sdk-common/actions/workflows/ci.yml