fix: re-add build-scss-to-css-map to package.json

[brian-smith-tcril]

Description

In https://github.com/openedx/paragon/tree/alpha#usage, one of the steps is running

npm run build-scss-to-css-map # creats scss-to-css-core.json and scss-to-css-components.json 

this was giving me a

npm ERR! Missing script: "build-scss-to-css-map"

error.

It seems it was removed in 9184d80, if this was intentional, I will close this PR and make one updating the README instead.

Post-merge Checklist

• Verify your changes were released to NPM at the expected version.
• If you'd like, share your contribution in #show-and-tell.
• 🎉 🙌 Celebrate! Thanks for your contribution.

[adamstankiewicz]

@brian-smith-tcril I believe removing this command was intentional. For example, in this open PR, that command is no longer mentioned in the README usage.

(Note, this PR appears way larger than it actually is (it's only a change to the README file!) presumably because of all the issues with ending up needing to essentially rewrite the git history on the alpha branch via git reset --hard <sha>...)

[brian-smith-tcril]

@adamstankiewicz sounds good! I'll close this and let the conversation continue in #2086