docs: fix troubleshooting link (googleapis#1861)

Fixes googleapis#1770

README.md

@@ -259,7 +259,7 @@ Java is a registered trademark of Oracle and/or its affiliates.
 [developer-console]: https://console.developers.google.com/
 [create-project]: https://cloud.google.com/resource-manager/docs/creating-managing-projects
 [cloud-sdk]: https://cloud.google.com/sdk/
-[troubleshooting]: https://github.com/googleapis/google-cloud-common/blob/main/troubleshooting/readme.md#troubleshooting
+[troubleshooting]: https://github.com/googleapis/google-cloud-java/blob/main/TROUBLESHOOTING.md
 [contributing]: https://github.com/googleapis/java-spanner-jdbc/blob/main/CONTRIBUTING.md
 [code-of-conduct]: https://github.com/googleapis/java-spanner-jdbc/blob/main/CODE_OF_CONDUCT.md#contributor-code-of-conduct
 [license]: https://github.com/googleapis/java-spanner-jdbc/blob/main/LICENSE