docs: add stability badge, CI table (#4)

Author: chingor13

README.md

@@ -2,8 +2,8 @@
 
 Java idiomatic client for [Google Cloud Recommender][api-reference].
 
-[![Kokoro CI][kokoro-badge-image]][kokoro-badge-link]
 [![Maven][maven-version-image]][maven-version-link]
+![Stability][stability-image]
 
 - [Product Documentation][product-docs]
 - [Client Library Documentation][javadocs]
@@ -91,11 +91,30 @@ information.
 
 Apache 2.0 - See [LICENSE][license] for more information.
 
+## CI Status
+
+Java Version | Status
+------------ | ------
+Java 7 | [![Kokoro CI][kokoro-badge-image-1]][kokoro-badge-link-1]
+Java 8 | [![Kokoro CI][kokoro-badge-image-2]][kokoro-badge-link-2]
+Java 8 OSX | [![Kokoro CI][kokoro-badge-image-3]][kokoro-badge-link-3]
+Java 8 Windows | [![Kokoro CI][kokoro-badge-image-4]][kokoro-badge-link-4]
+Java 11 | [![Kokoro CI][kokoro-badge-image-5]][kokoro-badge-link-5]
+
 [api-reference]: https://cloud.google.com/recommendations-ai/docs/apis
 [product-docs]: https://cloud.google.com/recommendations/docs
 [javadocs]: https://googleapis.dev/java/java-recommender/latest
-[kokoro-badge-image]: http://storage.googleapis.com/cloud-devrel-public/java/badges/java-recommender/master.svg
-[kokoro-badge-link]: http://storage.googleapis.com/cloud-devrel-public/java/badges/java-recommender/master.html
+[kokoro-badge-image-1]: http://storage.googleapis.com/cloud-devrel-public/java/badges/java-recommender/java7.svg
+[kokoro-badge-link-1]: http://storage.googleapis.com/cloud-devrel-public/java/badges/java-recommender/java7.html
+[kokoro-badge-image-2]: http://storage.googleapis.com/cloud-devrel-public/java/badges/java-recommender/java8.svg
+[kokoro-badge-link-2]: http://storage.googleapis.com/cloud-devrel-public/java/badges/java-recommender/java8.html
+[kokoro-badge-image-3]: http://storage.googleapis.com/cloud-devrel-public/java/badges/java-recommender/java8-osx.svg
+[kokoro-badge-link-3]: http://storage.googleapis.com/cloud-devrel-public/java/badges/java-recommender/java8-osx.html
+[kokoro-badge-image-4]: http://storage.googleapis.com/cloud-devrel-public/java/badges/java-recommender/java8-win.svg
+[kokoro-badge-link-4]: http://storage.googleapis.com/cloud-devrel-public/java/badges/java-recommender/java8-win.html
+[kokoro-badge-image-5]: http://storage.googleapis.com/cloud-devrel-public/java/badges/java-recommender/java11.svg
+[kokoro-badge-link-5]: http://storage.googleapis.com/cloud-devrel-public/java/badges/java-recommender/java11.html
+[stability-image]: https://img.shields.io/badge/stability-beta-yellow
 [maven-version-image]: https://img.shields.io/maven-central/v/com.google.cloud/google-cloud-recommender.svg
 [maven-version-link]: https://search.maven.org/search?q=g:com.google.cloud%20AND%20a:google-cloud-recommender&core=gav
 [authentication]: https://github.com/googleapis/google-cloud-java#authentication