Minor updates

[carlossanlop]

Some missed docs from System.Collections and System.IO.Compression.

The Compression ones are summaries for default constructors which often aren't declared in source code but show up as undoc in the dotnet-api-docs report.

[learn-build-service-prod]

Learn Build status updates of commit 2f338b6:

✅ Validation status: passed

File	Status	Preview URL	Details
xml/System.Collections.Concurrent/ConcurrentDictionary`2.xml	✅Succeeded	View
xml/System.Collections.Generic/HashSet`1.xml	✅Succeeded	View
xml/System.Collections.Generic/Stack`1.xml	✅Succeeded	View
xml/System.IO.Compression/BrotliCompressionOptions.xml	✅Succeeded	View
xml/System.IO.Compression/ZLibCompressionOptions.xml	✅Succeeded	View

For more details, please refer to the build report.

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• Try searching the learn.microsoft.com contributor guides
• Post your question in the Learn support channel

[buyaa-n]

Thanks!