Add bash highlighting

[aidan-casey]

I have a POC locally and will submit a PR later today.

[zepfietje]

Awesome, I was just looking for this! 😄
Anything I can do to help get a PR up, @aidan-casey?

[edent]

I'd also like to test this 👍

[brendt]

Don't leave us hanging now @aidan-casey !