docs(dotnet): Add .NET to metrics getting started

[Flash0ver]

DESCRIBE YOUR PR

PR #16054 adds the docs pages for sentry-dotnet.
This PR moves dotnet from "Upcoming SDKs" to "Supported SDKs".

All .NET platforms support Trace-connected Metrics, except Xamarin (dotnet.xamarin).

Related issue: getsentry/sentry-dotnet#4749
Merge after: #16054

IS YOUR CHANGE URGENT?

Help us prioritize incoming PRs by letting us know when the change needs to go live.

• Urgent deadline (GA date, etc.): 2026-02-06 (expected release of sentry-dotnet v6.1.0)
• Other deadline:
• None: Not urgent, can wait up to 1 week+

SLA

• Teamwork makes the dream work, so please add a reviewer to your PRs.
• Please give the docs team up to 1 week to review your PR unless you've added an urgent due date to it.
  Thanks in advance for your help!

PRE-MERGE CHECKLIST

Make sure you've checked the following before merging your changes:

• Checked Vercel preview for correctness, including links
• PR was reviewed and approved by any necessary SMEs (subject matter experts)
• PR was reviewed and approved by a member of the Sentry docs team

EXTRA RESOURCES

• Sentry Docs contributor guide

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Project	Deployment	Actions	Updated (UTC)
sentry-docs	Ready	Preview, Comment	Feb 4, 2026 4:18pm

1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
develop-docs	Ignored		Feb 4, 2026 4:18pm

[coolguyzone]

This looks good, thanks for the update 👍