Add sassc error message troubleshooting and make lint

[jskinne3]

🎫 Ticket

While working on LG-7711 discovered missing README items

🛠 Summary of changes

Updated README with:

1. advice for cannot load such file -- sassc error
2. how to lint code

📜 Testing Plan

Test the additions to the README:

• If you have sassc errors, execute make run and then cancel it
• Run make lint to confirm it works

🚀 Notes for Deployment

N/A

[aduth]

I'd be more concerned that sassc is running at all under any circumstance, since Sass compilation happens by an entirely separate process 🤔 Maybe we need to be configuring Rails to not try to process any Sass files?

[jskinne3]

I'd be more concerned that sassc is running at all under any circumstance, since Sass compilation happens by an entirely separate process 🤔 Maybe we need to be configuring Rails to not try to process any Sass files?

I'll refer this observation to @jmhooper from whom I got the technique I added to the README