Fix some links

Author: flori

README.rdoc

@@ -11,7 +11,7 @@ will be two variants available:
 * The quite a bit faster native extension variant, which is in parts
   implemented in C or Java and comes with its own unicode conversion
   functions and a parser generated by the ragel state machine compiler
-  http://www.cs.queensu.ca/~thurston/ragel .
+  http://www.complang.org/ragel/ .
 
 Both variants of the JSON generator generate UTF-8 character sequences by
 default. If an :ascii_only option with a true value is given, they escape all
@@ -65,20 +65,9 @@ with:
 
 == Compiling the extensions yourself
 
-If you want to build the extensions yourself you need rake:
-
-  You can get it from rubyforge:
-    http://rubyforge.org/projects/rake
-
-  or just type
-
-  # gem install rake
-
-  for the installation via rubygems.
-
 If you want to create the parser.c file from its parser.rl file or draw nice
-graphviz images of the state machines, you need ragel from: http://www.cs.queensu.ca/~thurston/ragel
-
+graphviz images of the state machines, you need ragel from:
+http://www.complang.org/ragel/
 
 == Usage
 
@@ -349,7 +338,7 @@ Ruby License, see https://www.ruby-lang.org/en/about/license.txt.
 
 The latest version of this library can be downloaded at
 
-* http://rubyforge.org/frs?group_id=953
+* https://rubygems.org/gems/json
 
 Online Documentation should be located at