NEWS: feature number for String#-@ compile-time optimization

[ruby-core:79971] [Feature #13295]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58142 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

NEWS

@@ -37,7 +37,7 @@ with all sufficient information, see the ChangeLog file or Redmine
   * String#-@ deduplicates unfrozen strings.  Already-frozen
     strings remain unchanged for compatibility.  [Feature #13077]
   * -"literal" (String#-@) optimized to return the same object
-    (same as "literal".freeze in Ruby 2.1+)
+    (same as "literal".freeze in Ruby 2.1+) [Feature #13295]
 
 === Stdlib updates (outstanding ones only)