File.OpenWrite doc improvements

[adamsitnik]

Summary

Some minor polishing:

1. remove redundant comments from the snippet
2. update the description to reflect the text that would actually got printed

Fixes #10813

[learn-build-service-prod]

Learn Build status updates of commit 750b86e:

✅ Validation status: passed

File	Status	Preview URL	Details
snippets/csharp/System.IO/FileInfo/OpenWrite/file openwrite.cs	✅Succeeded	View
xml/System.IO/FileInfo.xml	✅Succeeded	View

For more details, please refer to the build report.

For any questions, please:

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

[gewarren]

Thank you

[learn-build-service-prod]

Learn Build status updates of commit 8d4c207:

✅ Validation status: passed

File	Status	Preview URL	Details
snippets/csharp/System.IO/FileInfo/OpenWrite/file openwrite.cs	✅Succeeded	View
xml/System.IO/FileInfo.xml	✅Succeeded	View

For more details, please refer to the build report.

For any questions, please:

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