prepare 2.19.1 release (#226)

Author: LaunchDarklyCI

README.md

@@ -55,4 +55,3 @@ 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
-    * [Feature Flagging Guide](https://github.com/launchdarkly/featureflags/  "Feature Flagging Guide") for best practices and strategies