Fix PowerShell command typos in VM token usage

[pshelton-skype]

Updated PowerShell commands to use Invoke-RestMethod instead of Invoke-RestMeth (which does not exist).

Invoke-RestMethod is supported in PowerShell versions 5.1 through 7.6 (preview):

• https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.utility/invoke-restmethod?view=powershell-5.1
• https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.utility/invoke-restmethod?view=powershell-7.4
• https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.utility/invoke-restmethod?view=powershell-7.5
• https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.utility/invoke-restmethod?view=powershell-7.6

[prmerger-automator]

@pshelton-skype : Thanks for your contribution! The author(s) and reviewer(s) have been notified to review your proposed change.

[learn-build-service-prod]

Learn Build status updates of commit b40b54e:

✅ Validation status: passed

File	Status	Preview URL	Details
docs/identity/managed-identities-azure-resources/how-to-use-vm-token.md	✅Succeeded

For more details, please refer to the build report.

[SHERMANOUKO]

Handled here #1739

[ttorble]

Handled here #1739

@pshelton-skype and @SHERMANOUKO I'll close this PR now that 1739 has been merged. Thanks!