remove duplicate "Critical"

Author: PhilippSalvisberg

docs/4-language-usage/4-control-structures/2-case-if-decode-nvl-nvl2-coalesce/g-4230.md

@@ -3,8 +3,6 @@
 !!! danger "Critical"
     Efficiency, Reliability
 
-Critical
-
 ## Reason
 
 The `NVL` function always evaluates both parameters before deciding which one to use. This can be harmful if parameter 2 is either a function call or a select statement, as it will be executed regardless of whether parameter 1 contains a NULL value or not.