Clarify that SA1413 is also reported for enum members

Author: sharwell

documentation/SA1413.md

@@ -19,7 +19,7 @@
 
 ## Cause
 
-The last statement in a multi-line C# initializer is missing a trailing comma.
+The last statement in a multi-line C# initializer or list is missing a trailing comma.
 
 ### Rationale
 
@@ -31,7 +31,7 @@ continue to show the original author and commit for the item that was previously
 
 ## Rule description
 
-A violation of this rule occurs when the last statement of a C# initializer is missing a trailing comma.
+A violation of this rule occurs when the last statement of a C# initializer or list is missing a trailing comma.
 
 For example, the following code would generate one instance of this violation:
 
@@ -55,6 +55,8 @@ var x = new Barnacle
 };
 ```
 
+This diagnostic is also reported for other forms of comma-separated list, such as enum members.
+
 ## How to fix violations
 
 To fix a violation of this rule, add a trailing comma to the last statement in the initializer.