Add port number to jenkinsci.dev

Without the port number, I couldn't connect (connection would timeout). Adding 8080 to http://jenkinsci.dev allowed me to access the Jenkins dashboard.

Author: agentolivia

jenkins/README.md

@@ -24,7 +24,7 @@ Note: *If there are any errors during the course of running `vagrant up`, and it
 ### 3 - Configure your host machine to access the VM.
 
  1. [Edit your hosts file](http://www.rackspace.com/knowledge_center/article/how-do-i-modify-my-hosts-file), adding the line `192.168.76.76 jenkinsci.dev` so you can connect to the VM.
- 2. Open your browser and access [http://jenkinsci.dev/](http://jenkinsci.dev/).
+ 2. Open your browser and access [http://jenkinsci.dev:8080](http://jenkinsci.dev:8080).
 
 ## Notes