Fix README to reflect github gem installation

Fix README instructions for building your own gem
Fix VERSION - not sure why it was set to 3.0.0

README.rdoc

@@ -23,10 +23,15 @@ A release and a gem are forthcoming.
 
 == Installation
 
-Until the gem release is made your best bet is to build the gem yourself and install it.
+=== From GitHub hosted gems
+
+  % sudo gem sources -a http://gems.github.com # (you only need to do this once)
+  % sudo gem install rubyist-aasm
+
+=== Building your own gems
 
   % rake gem
-  % sudo gem install pkg/aasm-3.0.0.gem
+  % sudo gem install pkg/aasm-0.0.2.gem
 
 
 == Simple Example

lib/version.rb

@@ -1,5 +1,5 @@
 module AASM
   module VERSION
-    STRING = '3.0.0'
+    STRING = '0.0.2'
   end
 end