Update ExchangePowerShellSnapin.yaml

Fix correct name of pssnapin module

Hunting Queries/SecurityEvent/ExchangePowerShellSnapin.yaml

@@ -15,7 +15,7 @@ query: |
   | where EventID == 4688
   | where Process has_any ("cmd.exe", "powershell.exe", "PowerShell_ISE.exe")
   | where isnotempty(CommandLine)
-  | where CommandLine contains "Add-PSSnapin Microsoft.Exchange.Powershell.Snapin"
+  | where CommandLine contains "Add-PSSnapin Microsoft.Exchange.Management.Powershell.Snapin"
   | summarize FirstSeen = min(TimeGenerated), LastSeen = max(TimeGenerated) by Computer, Account, CommandLine 
   | extend timestamp = FirstSeen, AccountCustomEntity = Account, HostCustomEntity = Computer
 entityMappings:
@@ -26,4 +26,4 @@ entityMappings:
   - entityType: Host
     fieldMappings:
       - identifier: FullName
-        columnName: HostCustomEntity
+        columnName: HostCustomEntity