docs: update refs and refs.local API docs

Author: Alan Shaw

SPEC/REFS.md

@@ -31,22 +31,21 @@
 
 | Type | Description |
 | -------- | -------- |
-| `Promise<Array>` | An array representing the links (references) |
+| `AsyncIterable<Object>` | An async iterable that yields objects representing the links (references) |
+
+Each yielded object is of the form:
 
-example of the returned array:
 ```js
 {
-  ref: "myref",
-  err: "error msg"
+  ref: string,
+  err: Error | null
 }
 ```
 
 **Example:**
 
 ```JavaScript
-const refs = await ipfs.refs(ipfsPath, { recursive: true })
-
-for (const ref of refs) {
+for await (const ref of ipfs.refs(ipfsPath, { recursive: true })) {
   if (ref.err) {
     console.error(ref.err)
   } else {
@@ -66,33 +65,28 @@ for (const ref of refs) {
 
 | Type | Description |
 | -------- | -------- |
-| `Promise<Array>` | An array representing all the local references |
+| `AsyncIterable<Object>` | An async iterable that yields objects representing the links (references) |
+
+Each yielded object is of the form:
 
-example of the returned array:
 ```js
 {
-  ref: "myref",
-  err: "error msg"
+  ref: string,
+  err: Error | null
 }
 ```
 
 **Example:**
 
 ```JavaScript
-ipfs.refs.local(function (err, refs) {
-  if (err) {
-    throw err
-  }
-
-  for (const ref of refs) {
-    if (ref.err) {
-      console.error(ref.err)
-    } else {
-      console.log(ref.ref)
-      // output: "QmHash"
-    }
+for await (const ref of ipfs.refs.local()) {
+  if (ref.err) {
+    console.error(ref.err)
+  } else {
+    console.log(ref.ref)
+    // output: "QmHash"
   }
-})
+}
 ```
 
 [examples]: https://github.com/ipfs/interface-ipfs-core/blob/master/src/files-regular