Add reference to docgen.proto in README
@@ -13,5 +13,7 @@ bazel build scripts:docgen
bazel-bin/scripts/docgen --spec_file path/to/your/README.yaml > README.md
```
-For an example of README.yaml and README.md files, see
+For an example of `README.yaml` and `README.md` files, see
[mysql-docker repo](https://github.com/GoogleCloudPlatform/mysql-docker).
+The yaml data follows the structure defined in
+[`docgen.proto`](lib/proto/docgen.proto).
