Docs: Remove payload-mailing plugin example

Remove the @xtr-dev/payload-mailing integration example to keep the documentation focused on the core plugin functionality and custom email service integration pattern.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

README.md

@@ -303,94 +303,6 @@ notificationsPlugin({
 })
 ```
 
-### Example: Using @xtr-dev/payload-mailing
-
-```typescript
-import { notificationsPlugin } from '@xtr-dev/payload-notifications'
-import { mailingPlugin } from '@xtr-dev/payload-mailing'
-
-// Configure the mailing plugin
-const mailing = mailingPlugin({
-  // ... your mailing config
-})
-
-// Add email notifications using collection overrides
-const notifications = notificationsPlugin({
-  channels: [{ id: 'default', name: 'Default' }],
-  collectionOverrides: {
-    notifications: (config) => ({
-      ...config,
-      hooks: {
-        ...config.hooks,
-        afterChange: [
-          ...(config.hooks?.afterChange || []),
-          async ({ doc, operation, req }) => {
-            if (operation === 'create') {
-              try {
-                // Get recipient details
-                let recipientId = doc.recipient
-                if (typeof recipientId === 'object' && recipientId?.id) {
-                  recipientId = recipientId.id
-                }
-
-                if (!recipientId) return
-
-                const recipient = await req.payload.findByID({
-                  collection: 'users',
-                  id: recipientId
-                })
-
-                if (!recipient?.email) return
-
-                // Extract plain text from rich text message
-                const extractText = (richText: any[]): string => {
-                  return richText
-                    .map(block =>
-                      block.children
-                        ?.map((child: any) => child.text)
-                        .join('')
-                    )
-                    .join('\n')
-                }
-
-                const messageText = extractText(doc.message)
-
-                // Send email using payload-mailing
-                await req.payload.create({
-                  collection: 'emails',
-                  data: {
-                    to: recipient.email,
-                    subject: doc.title,
-                    text: messageText,
-                    html: `
-                      <h2>${doc.title}</h2>
-                      <div>${messageText}</div>
-                      <p><a href="${process.env.PAYLOAD_PUBLIC_URL}/admin/collections/notifications/${doc.id}">View notification</a></p>
-                    `,
-                  }
-                })
-
-                console.log(`Email queued for ${recipient.email}`)
-              } catch (error) {
-                console.error('Failed to send notification email:', error)
-              }
-            }
-          }
-        ]
-      }
-    })
-  }
-})
-
-export default buildConfig({
-  plugins: [
-    mailing,
-    notifications,
-  ],
-  // ... rest of config
-})
-```
-
 **Important Notes:**
 - Always spread existing hooks (`...config.hooks`) to preserve plugin functionality
 - Use the spread operator for hook arrays (`...(config.hooks?.afterChange || [])`)