Update CONTRIBUTING.md

[jeroenrosendaal]

Updated "Devleoping" to "Developing"

[ShaMan123]

thanks

[ShaMan123]

@jeroenrosendaal the guide has been rewritten. After reading it, do you any comments? something needs more refining?

[jeroenrosendaal]

@ShaMan123 I think the Developing section is a bit confusing if you never used codesandbox before. I tried using it but dit not succeed. I also tried building the project manually but came across some errors regarding the conversion to typescript files. Seems like the references inside the build.js file are not updated yet.

[ShaMan123]

1. build.js is deprecated - we switched to a new build system
2. codesandbox is not directly related the the developing sectin. Please elaborate

[jeroenrosendaal]

@ShaMan123 What kind of build system do you use currently? I would like to test and contribute to the code. I've had some experience with the build.js. I assumed that codesandbox was the 'new way'.

[ShaMan123]

we moved to rollup
the guide covers how to use the commands
npm run build etc.

[jeroenrosendaal]

What guide are you referencing to?
I followed https://github.com/fabricjs/fabric.js#building section.
But npm run build did indeed the trick.

[ShaMan123]

Ahh I see
That is on it's way out #8189

[ShaMan123]

look here README

[jeroenrosendaal]

Thanks!