Add missing link references to example.md documentation

Author: kuba-kubula

docs/example.md

@@ -57,3 +57,7 @@ For more complex examples applications, please refer to:
 
 - [Express.js example application](http://github.com/apiaryio/dredd-example)
 - [Ruby on Rails example application](https://github.com/theodorton/dredd-test-rails)
+
+
+[API Blueprint]: http://apiblueprint.org/
+[Express.js]: http://expressjs.com/starter/hello-world.html

docs/overview.md

@@ -207,7 +207,7 @@ Generally, if you want to add Dredd to your existing test suite, you can just sa
 In some eco-systems, there is native support for adding Dredd to
 
 - [grunt-dredd](https://github.com/mfgea/grunt-dredd) a grunt task wrapper
-- [dredd-rack]( https://github.com/gonzalo-bulnes/dredd-rack) a rake task and rack wrapper
+- [dredd-rack](https://github.com/gonzalo-bulnes/dredd-rack) a rake task and rack wrapper
 
 ## Continuous Integration