Update Set-OwaMailboxPolicy.md

CalendarEnabled is an on-prem only parameter , although have some dependency on weatherenabled however does not do much on it's own in EXO so updating it.

Author: qaehtesh

exchange/exchange-ps/exchange/Set-OwaMailboxPolicy.md

@@ -585,6 +585,8 @@ Accept wildcard characters: False
 ```
 
 ### -CalendarEnabled
+This parameter is functional only in on-premises Exchange.
+
 The CalendarEnabled parameter specifies whether to enable or disable the calendar in Outlook Web App. Valid values are:
 
 - $true: The Calendar is available in Outlook Web App. This is the default value.