Confusing terminology in the figures

[emanjon]

• The Client in the first figures are likely a web server not a CoAP client at all (The server thinks it is the CoAP client that sent the request). Rename Client to Victim?

• The server in the multicast attacks are more than one. Should at least be changes to servers. Maybe update the figure with several endpoint.

[emanjon]

Figures updates in master. Also added svg.

Might need some more text to explain the roles Victim and Foe

[emanjon]

Fixed in master