Update Set-AzureRmVMDiskEncryptionExtension.md

[mestew]

I happened to be testing a similar script and think I ran across a few small issues with the examples.

1. $KEKName not set in examples 3&4
2. New-AzureRmADApplication seems to use -CertValue rather than -KeyValue and -KeyType https://docs.microsoft.com/en-us/powershell/module/azurerm.resources/new-azurermadapplication?view=azurermps-5.7.0
3. Looks like the KEK bit is missing from Set-AzureRmVMDiskEncryptionExtension in Example 4 for cert + KEK.

Description

Checklist

• I have read the Submitting Changes section of CONTRIBUTING.md
• The title of the PR is clear and informative
• The appropriate change log has been updated
• The PR does not introduce breaking changes
• If applicable, the changes made in the PR have proper test coverage
• For public API changes to cmdlets:
  • the changes have gone through a cmdlet design review
  • the cmdlet markdown files were generated using the platyPS module

[azuresdkci]

Can one of the admins verify this patch?

[mestew]

I just realized I stuck this in the preview branch rather than master (oops, I didn't verify, sorry). Let me know if you want me to close this PR and just do a new one against master

[cormacpayne]

@azuresdkci add to whitelist

[cormacpayne]

@mestew Hey Meghan, thanks for creating this PR 😀 I pushed a commit to your fork/branch that updates another Set-AzureRmVMDiskEncryptionExtension.md file that we have in our repository. Our default branch is preview, so your did the right thing opening the PR against that branch.

@ejarvi Hey Eric, would you mind reviewing the change made to this markdown file when you get the chance?

[ejarvi]

Yes - reviewed the changes and they look correct, thank you Meghan for catching this.