fixed formatting

o365/custom-theme.md

@@ -12,7 +12,7 @@ Get-Module -Name Microsoft.Online.SharePoint.PowerShell -ListAvailable | Select
 Install-Module -Name Microsoft.Online.SharePoint.PowerShell
 # Connect
 Connect-SPOService -Url https://EnterYouTenantHere-admin.sharepoint.com
-````
+```
 ### Install Theme
 https://docs.microsoft.com/en-us/powershell/module/sharepoint-online/Add-SPOTheme?view=sharepoint-ps
 ```