Publish dotnetup telemetry documentation to Microsoft Learn

## Summary

The `https://aka.ms/dotnetup-telemetry` short link currently points to the telemetry documentation in the `release/dnup` branch on GitHub:
https://github.com/dotnet/sdk/blob/release/dnup/src/Installer/dotnetup/docs/telemetry-notice.txt

This documentation should eventually be published to Microsoft Learn alongside the .NET CLI telemetry documentation.

## Current State

- Telemetry doc exists at: `src/Installer/dotnetup/docs/telemetry-notice.txt`
- aka.ms link points to GitHub (temporary)
- Documentation follows the same format as .NET CLI telemetry docs

## Action Items

- [ ] Convert telemetry-notice.txt to proper Microsoft Learn markdown format
- [ ] Submit documentation to dotnet/docs repository
- [ ] Coordinate with docs team for review and publication
- [ ] Update aka.ms/dotnetup-telemetry redirect to point to the MS Learn page
- [ ] Ensure documentation is kept in sync with any telemetry changes

## Suggested MS Learn Location

The documentation should live near the existing .NET CLI telemetry docs:
- Current CLI telemetry: https://aka.ms/dotnet-cli-telemetry
- Proposed dotnetup telemetry: `docs/core/tools/dotnetup-telemetry.md` (or similar)

## Related

- PR: https://github.com/nagilson/sdk/pull/10
- Current doc: https://github.com/dotnet/sdk/blob/release/dnup/src/Installer/dotnetup/docs/telemetry-notice.txt
- .NET CLI telemetry doc: https://learn.microsoft.com/dotnet/core/tools/telemetry