message: docs: document version support goals
diff: @@ -137,6 +137,27 @@ has instructions for running the samples.
  The [Google Cloud Pub/Sub Node.js Client API Reference][client-docs] documentation
  also contains samples.
  +## Supported Node.js Versions
  +
  +Our client libraries follow the [Node.js release schedule](https://nodejs.org/en/about/releases/).
  +Libraries are compatible with all current _active_ and _maintenance_ versions of
  +Node.js.
  +
  +Client libraries targetting some end-of-life versions of Node.js are available, and
  +can be installed via npm [dist-tags](https://docs.npmjs.com/cli/dist-tag).
  +The dist-tags follow the naming convention `legacy-(version)`.
  +
  +_Legacy Node.js versions are supported as a best effort:_
  +
  +* Legacy versions will not be tested in continuous integration.
  +* Some security patches may not be able to be backported.
  +* Dependencies will not be kept up-to-date, and features will not be backported.
  +
  +#### Legacy tags available
  +
  +* `legacy-8`: install client libraries from this dist-tag for versions
  + compatible with Node.js 8.
  +
  ## Versioning
  This library follows [Semantic Versioning](http://semver.org/).
  @@ -160,6 +181,12 @@ More Information: [Google Cloud Platform Launch Stages][launch_stages]
  Contributions welcome! See the [Contributing Guide](https://github.com/googleapis/nodejs-pubsub/blob/master/CONTRIBUTING.md).
  +Please note that this `README.md`, the `samples/README.md`,
  +and a variety of configuration files in this repository (including `.nycrc` and `tsconfig.json`)
  +are generated from a central template. To edit one of these files, make an edit
  +to its template in this
  +[directory](https://github.com/googleapis/synthtool/tree/master/synthtool/gcp/templates/node_library).
  +
  ## License
  Apache Version 2.0
  