Adjust list macro docs

editions/tw5.com/tiddlers/macros/ListMacro.tid

@@ -15,7 +15,7 @@ There are several variants of the macro:
 |1st |filter |Filter expression | |
 |2nd |type |HTML tag to be used for the list wrapper |"ul" |
 |3rd |subtype |HTML tag to be used for list entries  |"li" |
-|4th |class |The list element `<ul>` or `<ol>` gets a CSS class. eg: `<ul class="three-columns">` | |
+|4th |class |An optional CSS class to be applied to the list wrapper element (eg `<ul class="three-columns">`) | |
 
 ! Examples