Update common.md

Author: danieljackins

src/connections/spec/common.md

@@ -75,7 +75,25 @@ Here's an example of these common fields in raw JSON:
     },
     "groupId": "12345",
     "timezone": "Europe/Amsterdam",
-    "userAgent": "Mozilla/5.0 (iPhone; CPU iPhone OS 9_1 like Mac OS X) AppleWebKit/601.1.46 (KHTML, like Gecko) Version/9.0 Mobile/13B143 Safari/601.1"
+    "userAgent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/113.0.0.0 Safari/537.36",
+    "userAgentData": {
+      "brands": [
+        {
+          "brand": "Google Chrome",
+          "version": "113"
+        },
+        {
+          "brand": "Chromium",
+          "version": "113"
+        },
+        {
+          "brand": "Not-A.Brand",
+          "version": "24"
+        }
+      ],
+      mobile: false,
+      platform: 'macOS'
+    }
   },
   "integrations": {
     "All": true,
@@ -134,6 +152,7 @@ Context is a dictionary of extra information that provides useful context about
 | `groupId`   | String  | Group / Account ID. <br><br> This is useful in B2B use cases where you need to attribute your non-group calls to a company or account. It is relied on by several Customer Success and CRM tools.                                                                                                               |
 | `traits`    | Object  | Dictionary of `traits` of the current user. <br><br> This is useful in cases where you need to `track` an event, but also associate information from a previous `identify` call. You should fill this object the same way you would fill traits in an [identify call](/docs/connections/spec/identify/#traits). |
 | `userAgent` | String  | User agent of the device making the request.                                                                                                                                                                                                                                                                    |
+| `userAgentData` | Object | User agent data of the device making the request. Always contains `brands`, `mobile`, `platform`, and may contain `bitness`, `model`, `platformVersion`,`uaFullVersion`, `fullVersionList`, `wow64`, if [requested](docs/connections/sources/catalog/libraries/website/javascript/#client-hints) and available. <br><br> Only populates if the [Client Hints API](https://developer.mozilla.org/en-US/docs/Web/API/User-Agent_Client_Hints_API) is available on the browser. <br><br> This may contain more information than is available in the `userAgent` in some cases.                                                                                                                                |
 | `channel`   | String  | where the request originated from: server, browser or mobile                                                                                                                                                                                                                                                    |
 
 
@@ -180,6 +199,7 @@ Other libraries only collect `context.library`, any other context variables must
 | screen.width             |              | ✅             | ✅                 |
 | traits                   |              | ✅             | ✅                 |
 | userAgent                | ✅            |               | ✅                 |
+| userAgentData*           | ✅           |                |                    |
 | timezone                 |              | ✅             | ✅                 |
 
 - IP Address isn't collected by Segment's libraries, but is instead filled in by Segment's servers when it receives a message for **client side events only**.
@@ -188,6 +208,8 @@ Other libraries only collect `context.library`, any other context variables must
   
 - The Android library collects `screen.density` with [this method](/docs/connections/spec/common/#context-fields-automatically-collected).
 
+- userAgentData is only collected if the [Client Hints API](https://developer.mozilla.org/en-US/docs/Web/API/User-Agent_Client_Hints_API) is available on the browser.
+
 To pass the context variables which are not automatically collected by Segment's libraries, you must manually include them in the event payload. The following code shows how to pass `groupId` as the context field of Analytics.js's `.track()` event:
 
 ```js