chore(README.md): add notes regarding Coder integration (#341)

Co-authored-by: Mathias Fredriksson <mafredri@gmail.com>
(cherry picked from commit 7fe1900)

README.md

@@ -53,6 +53,27 @@ Exit the container, and re-run the `docker run` command... after the build compl
 > If you need to bypass this behavior for any reason, you can bypass this safety check by setting
 > `ENVBUILDER_FORCE_SAFE=true`.
 
+## Usage with Coder
+
+Coder provides sample
+[Docker](https://github.com/coder/coder/tree/main/examples/templates/devcontainer-docker)
+and
+[Kubernetes](https://github.com/coder/coder/tree/main/examples/templates/devcontainer-kubernetes)
+templates for use with Envbuilder. You can import these templates and modify them to fit
+your specific requirements.
+
+Below are some specific points to be aware of when using Envbuilder with a Coder
+deployment:
+
+- The `ENVBUILDER_INIT_SCRIPT` should execute `coder_agent.main.init_script` in
+  order for you to be able to connect to your workspace.
+- In order for the Agent init script to be able to fetch the agent binary from
+  your Coder deployment, the resulting Devcontainer must contain a download tool
+  such as `curl`, `wget`, or `busybox`.
+- `CODER_AGENT_TOKEN` should be included in the environment variables for the
+  Envbuilder container. You can also set `CODER_AGENT_URL` if required.
+
+
 ### Git Branch Selection
 
 Choose a branch using `ENVBUILDER_GIT_URL` with a _ref/heads_ reference. For instance: