Added static help link to Transistor integration setting (#26368)

ref
https://linear.app/ghost/issue/NY-1017/transistor-turn-on-and-customize-flow

- The flow to turn on the Transistor integration happens in many places
and people should be aware of the steps. In this first version, we are
adding a bookmark-like link to the Transistor integration help page.

Author: peterzimon

apps/admin-x-settings/src/assets/images/integrations/ghost-transistor.png

@@ -1,4 +1,5 @@
 import APIKeys from './api-keys';
+import BookmarkThumb from '../../../../assets/images/integrations/ghost-transistor.png';
 import IntegrationHeader from './integration-header';
 import NiceModal from '@ebay/nice-modal-react';
 import {ConfirmationModal, Form, Icon, Modal, Toggle} from '@tryghost/admin-x-design-system';
@@ -119,6 +120,19 @@ const TransistorModal = NiceModal.create(() => {
                         ]} />
                     )}
                 </Form>
+                {enabled &&
+                    <div className='mt-5 flex flex-col items-center'>
+                        <a className='w-100 flex flex-col items-stretch justify-between overflow-hidden rounded-md bg-grey-75 transition-all hover:border-grey-400 hover:bg-grey-100 md:flex-row' href="https://ghost.org/integrations/transistor/" rel="noopener noreferrer" target="_blank">
+                            <div className='order-2 px-7 py-5 md:order-1'>
+                                <div className='font-semibold'>How to use Transistor in Ghost</div>
+                                <div className='mt-1 text-sm text-grey-800 dark:text-grey-500'>Learn how to connect Transistor with Ghost to offer private podcasts in Portal and embed Transistor cards in your posts and pages.</div>
+                            </div>
+                            <div className='order-1 hidden w-[200px] shrink-0 items-center justify-center overflow-hidden md:!visible md:order-2 md:!flex'>
+                                <img alt="Bookmark Thumb" className='min-h-full min-w-full shrink-0' src={BookmarkThumb} />
+                            </div>
+                        </a>
+                    </div>
+                }
             </div>
         </Modal>
     );