docs to ruby 2.0

doc/install/installation.md

@@ -86,8 +86,8 @@ Remove the old Ruby 1.8 if present
 Download Ruby and compile it:
     mkdir /tmp/ruby && cd /tmp/ruby
-    curl --progress http://ftp.ruby-lang.org/pub/ruby/1.9/ruby-1.9.3-p392.tar.gz | tar xz
-    cd ruby-1.9.3-p392
+    curl --progress ftp://ftp.ruby-lang.org/pub/ruby/2.0/ruby-2.0.0-p247.tar.gz | tar xz
+    cd ruby-2.0.0-p247
     ./configure
     make
     sudo make install