update readme with info on survey metadata Cloud Build

README.md

@@ -6,3 +6,6 @@ How to use this repo:
 * [Issues](https://github.com/flutter/uxr/issues) are for tracking tasks in an active research study we conduct in public. Resolutions of issues usually are achieved by changes made to files in the repo (including the wiki). Anyone can post in this section.
 * [Discussions](https://github.com/flutter/uxr/discussions) are for having open-ended conversations about a research topic. There is no expectation that those conversations must reach a resolution nor closure. Anyone can post in this section.
 * [Wiki](https://github.com/flutter/uxr/wiki) is used to host public research documents that we do not expect frequent changes or do not expect community contributons. Only maintainers of this repo can edit the wiki section.
+
+## Survey Metadata
+When a PR is merged to update survey metadata located in `surveys`, you can verify that the directory has been successfully pushed to Google Cloud Storage by visiting [go/flutter-uxr-gcs-build](go/flutter-uxr-gcs-build). Please contact @KhanhNwin if you need access.