Added news entries of RDoc and Rubygems.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@60156 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

NEWS

@@ -159,6 +159,18 @@ with all sufficient information, see the ChangeLog file or Redmine
   * New constants:
     * Ripper::EXPR_BEG and so on for Ripper#state.
 
+* RDoc
+
+  * Update RDoc 6.0.0.beta3.
+    * Change lexer IRB based one to Ripper. It much improves the speed of generating document. 
+    * https://github.com/ruby/rdoc/pull/512
+
+* Rubygems
+
+  * Update Rubygems 2.6.14.
+    * http://blog.rubygems.org/2017/08/27/2.6.13-released.html
+    * http://blog.rubygems.org/2017/10/09/unsafe-object-deserialization-vulnerability.html
+
 * Set
   * Add Set#to_s as alias to #inspect [Feature #13676]
   * Add Set#=== as alias to #include? [Feature #13801]