Update readme with install updates

[joshmedeski]

• Drop the $ because when you copy to the clipboard you end up with an invalid command.
• Add yarn snippet (for quick copying)

[lukeed]

thank you, but this is pretty standard. i know the $ is included as part of the new COPY button on the snippet, but I still rather reiterate (thru convention) that its a terminal command

[joshmedeski]

Okay, thanks for responding, I understand your decision. I'm loving the speed benefits of this package!