Update about.md (change "data" field to "value")

The object returned from "await stream.read()" has two fields: "done" and "value", and not the "data" field destructured here.

Author: Amir Hasanzade

4-binary/03-blob/article.md

@@ -237,16 +237,16 @@ const readableStream = blob.stream();
 const stream = readableStream.getReader();
 
 while (true) {
-  // for each iteration: data is the next blob fragment
-  let { done, data } = await stream.read();
+  // for each iteration: value is the next blob fragment
+  let { done, value } = await stream.read();
   if (done) {
     // no more data in the stream
     console.log('all blob processed.');
     break;
   }
 
    // do something with the data portion we've just read from the blob
-  console.log(data);
+  console.log(value);
 }
 ```