More docs updates

core/modules/parsers/newwikitextparser/rules/heading.js

@@ -17,6 +17,12 @@ Wiki text block rule for headings. For example:
 
 The bang `!` must be the first thing on the line. Any white space before the text of the heading is ignored.
 
+A CSS can be applied to the heading as follows:
+
+{{{
+!{{myClass}} This heading will have the class `myClass`
+}}}
+
 \*/
 (function(){
 

core/modules/parsers/newwikitextparser/rules/list.js

@@ -31,6 +31,14 @@ Note that lists can be nested arbitrarily:
 ## Nine
 }}}
 
+A CSS class can be applied to a list item as follows:
+
+{{{
+* List item one
+*{{active}} List item two has the class `active`
+* List item three
+}}}
+
 \*/
 (function(){