add documentation for auctionDelay in userSync (#1459)

* add documentation for auctionDelay in userSync

* rephrase language

* add details to reference

* remove auction delay from sandbox

* remove spacing changes to sandbox

* remove spacing changes to sandbox

* remove spacing changes to sandbox

dev-docs/publisher-api-reference.md

@@ -1717,6 +1717,7 @@ For descriptions of all the properties that control user syncs, see the table be
 | `filterSettings` | Object  | Configure lists of adapters to include or exclude their user syncing based on the pixel type (image/iframe). |
 | `syncsPerBidder` | Integer | Number of registered syncs allowed per adapter. Default: `5`. To allow all, set to `0`.                 |
 | `syncDelay`      | Integer | Delay in milliseconds for syncing after the auction ends. Default: `3000`.                              |
+| `auctionDelay`      | Integer | Delay in milliseconds of the auction to sync user ids before auction. Continues auction once ids are synced or delay times out. Default: `0`.                              |
 | `enableOverride` | Boolean | Enable/disable publisher to trigger user syncs by calling `pbjs.triggerUserSyncs()`.  Default: `false`. |
 
 <a name="setConfig-ConfigureUserSyncing-UserSyncExamples" />
@@ -1745,6 +1746,16 @@ pbjs.setConfig({
 });
 {% endhighlight %}
 
+Delay auction to sync user ids first:
+
+{% highlight js %}
+pbjs.setConfig({
+    userSync: {
+        auctionDelay: 1000 
+    }
+});
+{% endhighlight %}
+
 Allow iframe-based syncs (the presence of a valid `filterSettings.iframe` object automatically enables iframe type user-syncing):
 
 {% highlight js %}