docs: Added account sync know issue.

      </li>

    </ul>

    <h4 id="account">

      Account sync

    </h4>

    <ul>

      <li>Account sync initiated from watch settings may not work reliably.

      Instead, add accounts from the setup flow of the Android Wear app, or using

      the Accounts settings for a device from the Android Wear app.

      </li>

      <li>The list of accounts that can be synced is the same as the list of accounts

      on the phone. So to add a new account, use the Android settings on the phone,

      and then proceed to Android Wear app to sync that account.

      </li>

    </ul>

    <h4 id="devices">

      Devices

    </h4>