Add missing documentation for APIs in System.Configuration

[joperezr]

Summary

Adding missing docs for two new serialization constructors on types inside System.Configuration.ConfigurationManager

Fixes dotnet/runtime#58660

[ghost]

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Issue Details

---

Summary

Adding missing docs for two new serialization constructors on types inside System.Configuration.ConfigurationManager

Fixes dotnet/runtime#58660

Author:	joperezr
Assignees:	-
Labels:	area-System.Configuration
Milestone:	-

[opbld32]

Docs Build status updates of commit f77092e:

✅ Validation status: passed

File	Status	Preview URL	Details
xml/System.Configuration/SettingsAttributeDictionary.xml	✅Succeeded	View
xml/System.Configuration/SettingsContext.xml	✅Succeeded	View

For more details, please refer to the build report.

Note: Broken links written as relative paths are included in the above build report. For broken links written as absolute paths or external URLs, see the broken link report.

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