NEWS: Add `RubyVM::AST.of` to NEWS [ci skip]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65615 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

NEWS

@@ -236,6 +236,9 @@ sufficient information, see the ChangeLog file or Redmine
     * RubyVM::AST.parse_file parses a given file and returns AST
       nodes.  [experimental]
 
+    * RubyVM::AST.of returns AST nodes of the given proc or method.
+      [experimental]
+
 [String]
 
   [New features]