Add usage videos (Fix #17)

[double-fault]

No description provided.

[double-fault]

Hmm, looks like the videos are not previewing on the README page. Hold on, please.

[double-fault]

Seems to preview now! I've added two asciicasts.

[GhostofGoes]

A few things. For the first video, the --version flag is redundant, and I'd rather it show usage of at least a few of the other arguments that do matter (-n for hosts and -i for interfaces). Two commands you could run would be get-mac -n 192.168.0.1 (replace IP with your Router's IP) and get-mac -i eth0 (or another interface on your machine).

Don't include the "exit" command in either video.

For the second video: Same as the first, show example of a remote host and a local interface.

[double-fault]

@GhostofGoes Sure, I'll do that! I'm slightly busy today with life, I'll be sure to make the new videos tomorrow.

[double-fault]

@GhostofGoes I've made the changes you've asked for. Although, the "exit" command in the recording seems to be a bug with asciinema (asciinema/discussions#34), and I could not remove it. I tried out some more tools like ttystudio and showterm, but none of them worked for me.

[GhostofGoes]

Oh, this is awesome! Thank you so much 😄