Doc another secret (open-telemetry#8709)

Author: trask

.github/repository-settings.md

@@ -63,7 +63,10 @@ for [`dependabot/**/**`](https://github.com/open-telemetry/community/blob/main/d
 * `GE_CACHE_USERNAME`
 * `GPG_PASSWORD` - stored in OpenTelemetry-Java 1Password
 * `GPG_PRIVATE_KEY` - stored in OpenTelemetry-Java 1Password
-* `GRADLE_ENTERPRISE_ACCESS_KEY`
+* `GRADLE_ENTERPRISE_ACCESS_KEY` - owned by [@trask](https://github.com/trask)
+  * Generated at https://ge.opentelemetry.io > My settings > Access keys
+  * format of env var is `ge.opentelemetry.io=<access key>`,
+    see [docs](https://docs.gradle.com/enterprise/gradle-plugin/#via_environment_variable)
 * `GRADLE_PUBLISH_KEY`
 * `GRADLE_PUBLISH_SECRET`
 * `OPENTELEMETRYBOT_GITHUB_TOKEN` - owned by [@trask](https://github.com/trask)