ai/worker: Add package documentation

Ported from original README in ai-worker repo

ai/worker/doc.go

@@ -0,0 +1,13 @@
+/*
+Package `worker` hosts the main AI worker logic for managing or using runner
+containers for processing inference requests on the Livepeer AI subnet. The
+package allows interacting with the [AI runner containers], and it includes:
+  - **Golang API Bindings** (./runner.gen.go): Generated from the AI runner's
+    OpenAPI spec. To re-generate them run: `make ai_worker_codegen`
+  - **Worker** (./worker.go): Listens for inference requests from the Livepeer
+    AI subnet and routes them to the AI runner.
+  - **Docker Manager** (./docker.go): Manages AI runner containers.
+
+[AI runner containers]: https://github.com/livepeer/ai-runner
+*/
+package worker