[lp_intro]Update lp

[longye-tian]

Dear John @jstac and Matt @mmcky ,

This pull request update lecture lp_intro.md according to #514

In particular, this pull request

• add explanation on 'iso-revenue lines'
• add commas in the numbers to be consistent
• I also find there is no need to add example environment in this lecture as all the examples are the main text.
• This lecture also pass the spelling/grammar check

Best ❤️ Longye

[netlify[bot]]

✅ Deploy Preview for taupe-gaufre-c4e660 ready!

Name	Link
🔨 Latest commit	980e784b97507caf60193d87a5558c984c2c2c69
🔍 Latest deploy log	https://app.netlify.com/sites/taupe-gaufre-c4e660/deploys/669f907435c12f00088d3eba
😎 Deploy Preview	https://deploy-preview-531--taupe-gaufre-c4e660.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[github-actions[bot]]

🚀 Deployed on https://669f926615cc1c04c5383a58--taupe-gaufre-c4e660.netlify.app