Updated schema with newTabPosition setting (#13469)

## Summary of the Pull Request
Updates schema with newTabPosition global setting, added in #13421

## PR Checklist
* [x] CLA signed. If not, go over [here](https://cla.opensource.microsoft.com/microsoft/Terminal) and sign the CLA
* [x] Documentation updated. If checked, please file a pull request on [our docs repo](https://github.com/MicrosoftDocs/terminal) and link it here: MicrosoftDocs/terminal#559
* [x] Schema updated.

## Detailed Description of the Pull Request / Additional comments
#13421 got merged, so I'm adding this one

Co-authored-by: Carlos Zamora <carlos.zamora@microsoft.com>

doc/cascadia/profiles.schema.json

@@ -1969,6 +1969,16 @@
           ],
           "type": "string"
         },
+        "newTabPosition": {
+          "default": "atTheEnd",
+          "description": "Specifies position of the new tab. Possible values are \"atTheEnd\" and \"afterCurrentTab\".",
+          "enum": [
+            "atTheEnd",
+            "afterCurrentTab"
+          ],
+          "type": "string"
+        }
+      },
         "autoHideWindow": {
           "default": false,
           "description": "If enabled, Terminal window will be hidden as soon as it loses focus.",