Update Math.xml

[RVerheggen]

Typing error in Note: availble -> available

Summary

There was a typing error in the first note (about MidpointRounding) : availble is changed to available

[opbld31]

Docs Build status updates of commit d3fbfdc:

✅ Validation status: passed

File	Status	Preview URL	Details
xml/System/Math.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 the docs.microsoft.com contributor guides
• Post your question in the Docs support channel

[gewarren]

Thank you @RVerheggen!