Replace link to MIMIC-II Vagrant repo with MIMIC-III

- Currently the buildmimic/vagrant README links to a repo
  that automatically downloads and loads the MIMIC II data into
  a Vagrant VM. This commit replaces the links and language in
  that README to reference a sister repo that downloads and
  loads the MIMIC III data.
- Leaves a link at the bottom of the README to the MIMIC II
  repo in case usage of that data is desired.
- Removes the sub-header that says "MIMIC-III version coming soon...".

buildmimic/vagrant/README.md

@@ -1,15 +1,18 @@
-# Vagrant VM for MIMIC II
+# Vagrant VM for MIMIC III
 
-## (MIMIC-III version coming soon...)
-
-See: [mimic-ii-vm](https://github.com/nsh87/mimic-ii-vm)
+See: [mimic-iii-vm](https://github.com/nsh87/mimic-iii-vm)
 
 Vagrant allows you to easily automate the creation of virtual machines.
-The [mimic-ii-vm](https://github.com/nsh87/mimic-ii-vm) repository will
-create a virtual machine with Vagrant, download the MIMIC II data, and
-make it accessible to you via command line or graphical interface with
-a single command.
+The [mimic-iii-vm](https://github.com/nsh87/mimic-iii-vm) repository will
+create a virtual machine with Vagrant, download version three of the
+MIMIC III data, and make it accessible to you via command line or graphical
+interface with a single command.
 
 The automated steps performed on the VM are similar to those in the
 [Install MIMIC locally](http://mimic.physionet.org/tutorials/install_mimic_locally/)
 instructions on the official website.
+
+<hr>
+
+If you would like to use the MIMIC II data, please use the
+[mimic-ii-vm](https://github.com/nsh87/mimic-ii-vm) repository, instead.