Netlify

**What use-case(s) is this template for? (e.g. CI, CD, Mobile, ML, Monorepos, etc.)**
CI, CD

**What platform(s) (if applicable) should this template target? (e.g. Docker, Kubernetes, Linux, iOS, etc.)**
[Netlify](https://www.netlify.com/)

**What language(s) (if applicable) should this template use? (e.g. Go, Ruby, Terraform, etc.)**
Javascript is probably the most applicable, but there could be more languages.

**Are there any specific tools this template should use? (e.g. `pip`, `Cypress`, `rails`, etc.)**
[`netlify-cli`](https://docs.netlify.com/cli/get-started/)

Review existing CI/CD templates in the buildkite/templates repository and the linked netlify-cli documentation first. Define the intended Netlify workflow and supported languages, then add a complete template whose CI and CD behavior can be exercised through netlify-cli.

Written by the indexing model from the issue text.