Description

Add documentation for Coder's Template Insights feature. This feature is currently undocumented.

The documentation should cover:

• What Template Insights are and their purpose
• How to access and use Template Insights
• What metrics and data are provided
• How to interpret the insights data
• Any configuration or setup requirements

Suggested location: A new page under admin/templates/ or integration into existing template management documentation.

Impact

Users and administrators are unable to discover or understand the Template Insights feature without documentation, limiting their ability to gain visibility into template usage and performance.

Links

• Slack thread: https://coder.slack.com/archives/C068RSN2F6K/p1764882093903819
• Related PR comment: feat: add flag to disable template insights #20940 (comment)