[Doc] No document related to enterprise policy enforcement for local sandbox

### Describe the bug

In sandbox document, there is only a description that local sandbox can be managed by Microsoft Intune or MDM, however, there is no detailed information about how enterprise user can config and use it:

> [Enterprise policy enforcement](https://docs.github.com/en/copilot/concepts/about-cloud-and-local-sandboxes?search-overlay-input=detailed+information+about+%3A+Enterprise+policy+enforcement+For+organizations+and+enterprises%2C+local+sandbox+policies+can+be+centrally+configured+and+enforced+using+Microsoft+Intune+and+other+MDM+%28mobile+device+management%29+platforms.+This+gives+administrators+control+over+how+Copilot+interacts+with+local+resources+across+managed+devices.&search-overlay-ask-ai=true#enterprise-policy-enforcement)
For organizations and enterprises, local sandbox policies can be centrally configured and enforced using Microsoft Intune and other MDM (mobile device management) platforms. This gives administrators control over how Copilot interacts with local resources across managed devices.

### Affected version

_No response_

### Steps to reproduce the behavior

_No response_

### Expected behavior

_No response_

### Additional context

_No response_

Start with the linked about-cloud-and-local-sandboxes documentation and inspect the Enterprise policy enforcement section. Document how enterprise users configure and use local sandbox policies through Microsoft Intune and other MDM platforms; done means the page provides detailed configuration and usage guidance beyond the existing overview.

索引モデルが issue の本文から書いたものです。