This commit adds a note and link on how to install vagrant-share before
the vagrant share tutorial starts. This ensures that users know they
need the plugin installed since it no longer comes with Vagrant core.
This commit ensures that a proper box is used during the project setup
tutorial. Otherwise later down the road uesrs will run into Vagrant
saying that the box `base` doesn't exist.
Brian Cain
Amit Bhardwaj
Brandon9598
Brandon Moore
Chris Roberts
Seth Vargo