Update vm-boot-optimization.md

[Kanik09]

ARM64 is now supported for VM boot optimization. Made changes to the public documentation accorindgly.

[prmerger-automator[bot]]

@Kanik09 : Thanks for your contribution! The author(s) have been notified to review your proposed change.

[learn-build-service-prod[bot]]

Learn Build status updates of commit acee1be:

:white_check_mark: Validation status: passed

File	Status	Preview URL	Details
articles/virtual-machines/vm-boot-optimization.md	:white_check_mark: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