Update Notes on Computer Networks

[s2t2]

Using some material from past courses in the slides. It would be good to adapt that material and add to this repo as well.

See:

• https://github.com/prof-rossetti/gwu-badm-2301-201509/blob/master/notes/information-system-components/networks-and-protocols.md
• https://github.com/prof-rossetti/southernct-csc-443-201701/tree/master/notes/computer-networks