chore: regenerate README (#269)

This PR was generated using Autosynth. 🌈


<details><summary>Log from Synthtool</summary>

```
2021-05-26 16:52:10,825 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-workflows/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-05-26 16:52:12,094 synthtool [DEBUG] > Wrote metadata to .github/readme/synth.metadata/synth.metadata.

```
</details>

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https://source.cloud.google.com/results/invocations/e65041f8-cb68-4e46-adf6-d9f0be0ee1fc/targets

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java-workflows/.github/readme/synth.metadata/synth.metadata

@@ -4,7 +4,7 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-workflows.git",
-        "sha": "a901f95055c13e57a8af9f71f05a54ffb21e2beb"
+        "sha": "91404cef3b9cef16c0e0c1e322a9eda0d4f80b24"
       }
     },
     {

java-workflows/README.md

@@ -8,9 +8,6 @@ Java idiomatic client for [Cloud Workflows][product-docs].
 - [Product Documentation][product-docs]
 - [Client Library Documentation][javadocs]
 
-> Note: This client is a work-in-progress, and may occasionally
-> make backwards-incompatible changes.
-
 ## Quickstart
 
 
@@ -85,9 +82,6 @@ Java 7 or above is required for using this client.
 This library follows [Semantic Versioning](http://semver.org/).
 
 
-It is currently in major version zero (``0.y.z``), which means that anything may change at any time
-and the public API should not be considered stable.
-
 ## Contributing
 
 
@@ -127,7 +121,7 @@ Java is a registered trademark of Oracle and/or its affiliates.
 [kokoro-badge-link-4]: http://storage.googleapis.com/cloud-devrel-public/java/badges/java-workflows/java8-win.html
 [kokoro-badge-image-5]: http://storage.googleapis.com/cloud-devrel-public/java/badges/java-workflows/java11.svg
 [kokoro-badge-link-5]: http://storage.googleapis.com/cloud-devrel-public/java/badges/java-workflows/java11.html
-[stability-image]: https://img.shields.io/badge/stability-beta-yellow
+[stability-image]: https://img.shields.io/badge/stability-ga-green
 [maven-version-image]: https://img.shields.io/maven-central/v/com.google.cloud/google-cloud-workflows.svg
 [maven-version-link]: https://search.maven.org/search?q=g:com.google.cloud%20AND%20a:google-cloud-workflows&core=gav
 [authentication]: https://github.com/googleapis/google-cloud-java#authentication