Add examples to dotnet-gcdump doc

[Copilot]

Summary

Adds Examples sections to dotnet-gcdump collect and dotnet-gcdump report commands, following the established pattern in dotnet-counters.md.

• dotnet-gcdump collect: 4 examples covering process ID, custom output path, process name with verbose, and custom timeout
• dotnet-gcdump report: 2 examples covering file-based and process-based report generation

Fixes #20138

Original prompt

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This section details on the original issue you should resolve

<issue_title>Add examples to dotnet-gcdump doc</issue_title>
<issue_description>Following the pattern of https://raw.githubusercontent.com/dotnet/docs/master/docs/core/diagnostics/dotnet-counters.md we should have an Examples h3 section following each Options h3 section.

Originally posted by @tdykstra in #19697

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Document Details

⚠ Do not edit this section. It is required for docs.microsoft.com ➟ GitHub issue linking.

• ID: 0aa2e42f-838c-92e9-1125-7540721952e6
• Version Independent ID: 665bb8b1-6024-24d1-46df-8ae4789fe1a1
• Content: dotnet-gcdump diagnostic tool - .NET CLI
• Content Source: docs/core/diagnostics/dotnet-gcdump.md
• Product: dotnet-fundamentals
• GitHub Login: @sywhang
• Microsoft Alias: suwhang

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Associated WorkItem - 537141</issue_description>

Comments on the Issue (you are @copilot in this section)

@adegeo Thanks :D @gewarren Close/reopen for priority label.

• Fixes Add examples to dotnet-gcdump doc #20138

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Internal previews

📄 File	🔗 Preview link
docs/core/diagnostics/dotnet-gcdump.md	docs/core/diagnostics/dotnet-gcdump

[Copilot]

Pull request overview

This PR successfully adds Examples sections to the dotnet-gcdump documentation, following the established pattern from dotnet-counters.md as requested in issue #20138.

Key changes:

• Added 4 examples for dotnet-gcdump collect covering common usage scenarios
• Added 2 examples for dotnet-gcdump report demonstrating both file-based and process-based reporting
• Included realistic command outputs to help users understand expected results