Add documentation comments to createFileOutput declaration

Author: mattt

lib/stream.js

@@ -98,6 +98,15 @@ function createReadableStream({ url, fetch, options = {} }) {
   });
 }
 
+/**
+ * Create a new readable stream for an output file
+ * created by running a Replicate model.
+ *
+ * @param {object} config
+ * @param {string} config.url The URL to connect to.
+ * @param {typeof fetch} [config.fetch] The URL to connect to.
+ * @returns {ReadableStream<Uint8Array>}
+ */
 function createFileOutput({ url, fetch }) {
   let type = "application/octet-stream";