feat: promote to GA (#166)

Release-As: 1.0.0

.repo-metadata.json

@@ -4,7 +4,7 @@
     "product_documentation": "https://cloud.google.com/iam/docs/troubleshooting-access",
     "api_description": "makes it easier to understand why a user has access to a resource or doesn't have permission to call an API. Given an email, resource, and permission, Policy Troubleshooter examines all Identity and Access Management (IAM) policies that apply to the resource. It then reveals whether the member's roles include the permission on that resource and, if so, which policies bind the member to those roles.",
     "client_documentation": "https://cloud.google.com/java/docs/reference/google-cloud-policy-troubleshooter/latest/history",
-    "release_level": "preview",
+    "release_level": "stable",
     "transport": "grpc",
     "language": "java",
     "repo": "googleapis/java-policy-troubleshooter",

README.md

@@ -8,9 +8,6 @@ Java idiomatic client for [IAM Policy Troubleshooter API][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
 
@@ -132,9 +129,6 @@ and on [google-cloud-java][g-c-j].
 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
 
@@ -175,7 +169,7 @@ 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-policy-troubleshooter/java8-win.html
 [kokoro-badge-image-5]: http://storage.googleapis.com/cloud-devrel-public/java/badges/java-policy-troubleshooter/java11.svg
 [kokoro-badge-link-5]: http://storage.googleapis.com/cloud-devrel-public/java/badges/java-policy-troubleshooter/java11.html
-[stability-image]: https://img.shields.io/badge/stability-preview-yellow
+[stability-image]: https://img.shields.io/badge/stability-stable-green
 [maven-version-image]: https://img.shields.io/maven-central/v/com.google.cloud/google-cloud-policy-troubleshooter.svg
 [maven-version-link]: https://search.maven.org/search?q=g:com.google.cloud%20AND%20a:google-cloud-policy-troubleshooter&core=gav
 [authentication]: https://github.com/googleapis/google-cloud-java#authentication