update get-spotheme command doc

Author: RongqiZ

sharepoint/sharepoint-ps/Microsoft.Online.SharePoint.PowerShell/Get-SPOTheme.md

@@ -31,7 +31,7 @@ The **Get-SPOTheme** cmdlet returns the settings for a named existing theme, or
 This example shows how to use the **Get-SPOTheme** cmdlet to return the settings for the `"Custom Cyan"` theme created in the example for the **Add-SPOTheme** cmdlet. Note that this example uses the PowerShell `ConvertTo-Json` filter to display the theme in JSON format.
 
 ```powershell
-Get-SPOTheme -Name "Custom Cyan" | ConvertTo-Json 4
+Get-SPOTheme -Name "Custom Cyan" | ConvertTo-Json -Depth 4
 ```
 
 ```Output