Add terminal recording to README

[camerondurham]

Suggestion:

Include asciicinema recording of installing the CLI. Not sure if I should have a recording on how to do it on Windows or just record demo on macOS.

Acceptance Criteria: (optional)

• [ ] make recording of installing on macOS
• [ ] record installing on Windows (stretch: maybe don't include this in README but in docs)
• [ ] make recording on Linux (jk, you should know how to do this on Linux anyways :grinning:)