feat: add decimal to binary project

[naomi-lgbt]

Checklist:

• [X] I have read freeCodeCamp's contribution guidelines.
• [X] My pull request has a descriptive title (not a vague title like Update index.md)

Closes #XXXXX

I couldn't find this in the repo. Pulled from: https://codesandbox.io/s/r886f?file=/index.js:0-2636

[jdwilkin4]

Hi @naomi-lgbt !

This project is in the decimal-to-binary directory It was merged back in July https://github.com/freeCodeCamp/CurriculumExpansion/pull/317

[naomi-lgbt]

Whoops! This is exactly what inspired #333 (which I am now realising needs a rebase).