✍️ update README

README.md

@@ -1,12 +1,30 @@
+![Screenshot of waypoint-plugin-nixpacks in HCP Waypoint](https://user-images.githubusercontent.com/26389321/218119583-9dabe325-9295-4098-90ac-b9f32ccb7b74.png)
+
+---
+
 # waypoint-plugin-nixpacks
 
-![CleanShot 2023-02-10 at 09 39 09@2x](https://user-images.githubusercontent.com/26389321/218119583-9dabe325-9295-4098-90ac-b9f32ccb7b74.png)
+This [Waypoint][waypoint] plugin builds OCI images using [`nixpacks`][nixpacks].
 
+This plugin only implements the [builder][builder] interface.
 
-This [Waypoint][waypoint] plugin builds OCI images using [nixpacks][nixpacks].
+## Building
 
-Check out the [examples](./examples) folder for usage examples.
+To build this plugin, run `make`. (See [`Makefile`](./Makefile) for more details.)
+A plugin binary will be built and outputted to the [`./bin`](./bin) folder as well as copied into the example project folder.
+
+This requires the following packages:
 
+- `go`
+- `protoc`
+- `protoc-gen-go`
+
+## Usage
+
+The Waypoint runner (such as the CLI) that ends up picking up a job (such as `waypoint build`) will need [`nixpacks`][nixpacks] installed.
+
+Check out the [examples](./examples) folder for usage examples.
 
-[waypoint]: https://developer.hashicorp.com/waypoint
+[builder]: https://developer.hashicorp.com/waypoint/docs/extending-waypoint/plugin-interfaces/builder
+[waypoint]: https://github.com/hashicorp/waypoint
 [nixpacks]: https://github.com/railwayapp/nixpacks