README: Improved project info

Author: Hank Brekke

README.md

@@ -2,4 +2,50 @@
 
 OpenStreetMap C++ tools available as an AWS Lambda Layer!
 
-More details coming soon.
+Run [Open Source Routing Machine](https://github.com/Project-OSRM/osrm-backend),
+[Osmium](https://github.com/osmcode/osmium-tool), and [Tilemaker](https://github.com/systemed/tilemaker) in AWS Lambda
+with precompiled C++ binaries ready to run on Amazon Linux 2023 (used by most Lambda runtimes).
+
+## Usage
+
+1. Open the [Releases](https://github.com/hnryjms/aws-lambda-layer-osmtools/releases) page and find the latest release.
+2. Copy the corresponding `Layer ARN` for your AWS Region. 
+3. In `AWS Console > Lambda > (function) > Code > Layers`, paste this `Layer ARN`.
+4. Save your function :)
+
+You can confirm your app is ready with an example handler like:
+
+### NodeJS:
+
+Ensure `@project-osrm/osrm` is marked as [`external`](https://esbuild.github.io/api/#external) in your bundling tools.
+
+```js
+import OSRM from "@project-osrm/osrm";
+import ChildProcess from "node:child_process";
+
+export const handler = async (event) => {
+  console.log(OSRM.version);
+  ChildProcess.execSync("osmium --version", { stdio: "inherit" });
+  ChildProcess.execSync("osrm-customize --version", { stdio: "inherit" });
+  ChildProcess.execSync("tilemaker --help", { stdio: "inherit" });
+
+
+  const response = {
+    statusCode: 200,
+    body: JSON.stringify('Hello from Lambda!'),
+  };
+  return response;
+};
+```
+
+## To Do
+
+- [ ] Split OSRM / Osmium / Tilemaker into individual, combinable layers
+- [ ] Add other runtime support (mainly CLI-only option)
+
+## Support
+
+This project is a part of my larger work on [Skyway.run](https://skyway.run), an indoor navigation app. If you find
+`aws-lambda-layer-osmtools` useful on your project, let me know and I can list you here.
+
+Contributors or sponsors very welcome :)