Add "Need help?" link to link screen

Co-authored-by: Evan Hahn <69474926+EvanHahn-Signal@users.noreply.github.com>

_locales/en/messages.json

@@ -1368,6 +1368,10 @@
     "message": "Learn more",
     "description": "Shown on the install screen if the QR code fails to load"
   },
+  "Install__support-link": {
+    "message": "Need help?",
+    "description": "Shown on the install screen. Link takes users to a support page"
+  },
   "Install__choose-device-name__description": {
     "message": "You'll see this name under \"Linked Devices\" on your phone",
     "description": "The subheader shown on the 'choose device name' screen in the device linking process"

ts/components/installScreen/InstallScreenQrCodeNotScannedStep.tsx

@@ -77,6 +77,9 @@ export const InstallScreenQrCodeNotScannedStep = ({
             />
           </li>
         </ol>
+        <a href="https://support.signal.org/hc/articles/360007320451#desktop_multiple_device">
+          {i18n('Install__support-link')}
+        </a>
       </div>
     </div>
   </div>