added details to requestBids: example and response (#2274)

dev-docs/publisher-api-reference.md

@@ -672,10 +672,31 @@ Request bids. When `adUnits` or `adUnitCodes` are not specified, request bids fo
 | requestObj.adUnitCodes | Optional | `Array of strings` | adUnit codes to request. Use this or `requestObj.adUnits`. Default to all `adUnitCodes` if empty. |
 | requestObj.adUnits | Optional | `Array of objects` | AdUnitObjects to request. Use this or `requestObj.adUnitCodes`. Default to all `adUnits` if empty. |
 | requestObj.timeout | Optional | `Integer` | Timeout for requesting the bids specified in milliseconds |
-| requestObj.bidsBackHandler | Optional | `function` | Callback to execute when all the bid responses are back or the timeout hits. Callback will be passed two parameters, the bids themselves and `timedOut`, which will be true if any bidders timed out. |
+| requestObj.bidsBackHandler | Optional | `function` | Callback to execute when all the bid responses are back or the timeout hits. Callback will be passed three parameters, the [bidResponses](#module_pbjs.getBidResponses) themselves, a `timedOut` flag (true if any bidders timed out) and the `auctionId`. |
 | requestObj.labels | Optional | `Array of strings` | Defines [labels](#labels) that may be matched on ad unit targeting conditions. |
 | requestObj.auctionId | Optional | `String` | Defines an auction ID to be used rather than having the system generate one. This can be useful if there are multiple wrappers on a page and a single auction ID is desired to tie them together in analytics. |
 
+Example call
+```
+pbjs.requestBids({
+    bidsBackHandler: sendAdserverRequest,
+    timeout: 1000,
+    labels: ["custom1"]
+});
+```
+
+Example parameters sent to the bidsBackHandler:
+```
+function sendAdserverRequest(bids, timedOut, auctionId) {
+    // bids
+    // {"test-div":{"bids":[{"bidderCode":"bidderA", ...}]}}
+    // See [getBidResponses function](#module_pbjs.getBidResponses) for details
+    // timedOut=false
+    // auctionId="130aad5e-eb1a-4b7d-8939-0663ba251887"
+    ...
+}
+```
+
 <hr class="full-rule">
 
 <a name="module_pbjs.addAdUnits"></a>