[Feature Request] - Add a notification system that informs users when a document they collaborate on or follow is modified.

Problem

CodiMD currently does not notify users when a document is updated. In collaborative workflows, this makes it easy to miss important changes, forcing users to manually check documents or rely on external communication tools.

Proposed Solution

Implement configurable notifications that are triggered when a document is modified. Notifications should respect user permissions and preferences.

Possible delivery channels:

• In-app notifications
• Email notifications
• Webhooks (for integrations such as Slack, Mattermost, etc.)

Proposed Features

• Subscribe/unsubscribe to notifications per document
• Default notification settings for document owners
• Configurable triggers (any edit, major changes only, metadata changes)

Use Cases

• Team members are notified when shared notes are updated
• Contributors are alerted when specifications change
• Reviewers know when a document has been edited and is ready for review

Additional Context

This feature would improve collaboration efficiency and make CodiMD more suitable for team-based documentation workflows.