Add documentation to System.Net.Http.Json APIs

[jozkee]

No description provided.

[opbld31]

Docs Build status updates of commit c261914:

✅ Validation status: passed

File	Status	Preview URL	Details
xml/System.Net.Http.Json/HttpClientJsonExtensions.xml	✅Succeeded	View
xml/System.Net.Http.Json/HttpContentJsonExtensions.xml	✅Succeeded	View
xml/System.Net.Http.Json/JsonContent.xml	✅Succeeded	View
xml/ns-System.Net.Http.Json.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.

For any questions, please:

• Try searching in the Docs contributor and Admin Guide
• See the frequently asked questions
• Post your question in the Docs support channel

[opbld33]

Docs Build status updates of commit c8d9309:

✅ Validation status: passed

File	Status	Preview URL	Details
xml/System.Net.Http.Json/HttpClientJsonExtensions.xml	✅Succeeded	View
xml/System.Net.Http.Json/HttpContentJsonExtensions.xml	✅Succeeded	View
xml/System.Net.Http.Json/JsonContent.xml	✅Succeeded	View
xml/ns-System.Net.Http.Json.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.

For any questions, please:

• Try searching in the Docs contributor and Admin Guide
• See the frequently asked questions
• Post your question in the Docs support channel