Mention the possibility of passing WorkerOptions

Author: aminya

docs/usage.md

@@ -167,7 +167,10 @@ const worker = await spawn(BlobWorker.fromText(MyWorker))
 Bundle this module and you will obtain a stand-alone bundle that has its worker inlined. This is particularly useful for libraries using threads.js.
 
 ### createWorker - select worker backend
-`createWorker` allows selecting the worker backend (among web, node, and tiny), and also if you want a blob worker. The second argument to the `createWorker` is an object that specifies `backend: 'web' | 'node' | 'tiny'` and `blob: boolean`.
+`createWorker` allows selecting the worker backend (among web, node, and tiny), and also if you want a blob worker.
+
+The second argument to the `createWorker` is an object that specifies `backend: 'web' | 'node' | 'tiny'` and `blob: boolean`.
+You can also pass other `WorkerOptions` in this object.
 
 `createWorker` uses dynamic imports to only import the needed implementation, so you can import the needed functions directly to reduce the bundle size.