Fix Az.KeyVault Syntax Errors

Author: Ziyue Zheng

src/KeyVault/KeyVault/help/Export-AzKeyVaultSecurityDomain.md

@@ -33,7 +33,7 @@ Exports the security domain data of a managed HSM for importing on another HSM.
 
 ### Example 1
 ```powershell
-Export-AzKeyVaultSecurityDomain -Name testmhsm -Certificates {./sd1, ./sd2,./sd3} -OutputPath sd.ps.json -Quorum 2
+Export-AzKeyVaultSecurityDomain -Name testmhsm -Certificates sd1.cer, sd2.cer, sd3.cer -OutputPath sd.ps.json -Quorum 2
 ```
 
 This command retrieves the managed HSM named testmhsm and saves a backup of that managed HSM security domain to the specified output file.

src/KeyVault/KeyVault/help/Update-AzKeyVaultSecret.md

@@ -63,8 +63,7 @@ ContosoVault, using the stored variables.
 
 ### Example 2: Delete the tags and content type for a secret
 ```powershell
-$ContentType= 'xml'
-Update-AzKeyVaultSecret -VaultName 'ContosoVault' -Name 'HR' -Version '9EEA45C6EE50490B9C3176A80AC1A0DF' -ContentType $ContentType -Tag @{}
+Update-AzKeyVaultSecret -VaultName 'ContosoVault' -Name 'HR' -Version '9EEA45C6EE50490B9C3176A80AC1A0DF' -ContentType '' -Tag @{}
 ```
 
 This command deletes the tags and the content type for the specified version of the secret named HR