Course Outro

[kolkhis]

We have the "Outro" page at the end of the coursework to mark the end of the course.
We could have a section saying something like:

Congratulations on making it to the end of the 16 week Enterprise Linux Administration course! You should now be able to confidently perform these tasks to administer Linux systems:

• Manage file permissions on the system
• Manage users and groups
• etc.

Maybe also include some information on the certification (when we nail down what that will look like for future students).
This should give the student a feeling of accomplishment and signify that they've reached end of the course.

[kolkhis]

On further inspection, I think we just need to change the order to put the outro.md directly after Unit 16.