Improve <system_error> operators reference

[Rageking8]

Summary:

• Enclose operator== and operator!= headings in backticks
• Augment and edit operator<< section
  • Remove unneeded indentation in its syntax
  • Add description, parameters, return value, and remarks reference
  • Add new example with output
• Edit metadata

[prmerger-automator]

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[learn-build-service-prod]

Learn Build status updates of commit 8ac274f:

✅ Validation status: passed

File	Status	Preview URL	Details
docs/standard-library/system-error-operators.md	✅Succeeded

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[TylerMSFT]

Thank you for adding the documentation for <<. Since the file was open, I did some minor code escaping (which prevents machine translation) and removed the old 'to be' stuff that our grammar tool won't like.

[learn-build-service-prod]

Learn Build status updates of commit 469ab7c:

✅ Validation status: passed

File	Status	Preview URL	Details
docs/standard-library/system-error-operators.md	✅Succeeded

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

[prmerger-automator]

PRMerger Results

Issue	Description
File Change Percent	This PR contains file(s) with more than 30% file change.

[TylerMSFT]

#sign-off