NEWS: indented heredoc [ci skip]

* NEWS: mention about indented here document.  [Feature #9098]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@52935 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

NEWS

@@ -14,6 +14,7 @@ with all sufficient information, see the ChangeLog file.
 === Language changes
 
 * frozen-string-literal pragma:
+
   * new pragma, frozen-string-literal has been experimentally introduced.
   * besides, --enable/--disable=frozen-string-literal options also have
     been introduced.
@@ -37,6 +38,11 @@ with all sufficient information, see the ChangeLog file.
     * attribute assignment is valid
           obj&.attr += 1
 
+* indented here document:
+
+  * new string literal, here document starts with `<<~`.
+    refer doc/syntax/literals.rdoc for more details.
+
 === Core classes updates (outstanding ones only)
 
 * ARGF