Bump version to 6.14.0 (#1371)

v6.13.1...master

We can then bump `ruby/ruby`'s RDoc to [set canonical
url](#1354).

Author: st0012

lib/rdoc/version.rb

@@ -5,6 +5,6 @@ module RDoc
   ##
   # RDoc version you are using
 
-  VERSION = '6.13.1'
+  VERSION = '6.14.0'
 
 end