Update CONTRIBUTING.md

[bcfletcher]

added language about installing node-canvas

[dlech]

Why do we need to install this manually?

[bcfletcher]

I'm a Mac so homebrew isn't installed by default. Nor are any of the requirements to build and compile pybricks.

It took me a while to figure out all the areas to get it to build.

[dlech]

I'm just a bit confused why we need node-canvas though. We don't have to install it on CI to build or test, so why do we have to install it locally?

[bcfletcher]

it was a dependency for a dependency. I will have to look tomorrow which one.Yarn install complained about it and refused to build pybricks I was trying to build pybricks on my MacMy purpose is I want to try to make some additions to pybricks:Add a Sync Master file support to pybricks. Basically make our hub_menu.py a “sync master” so if we  edit a task or our robot library and hit play to push code to the  robot it actually sync the hub_menu and its dependencies Add telemetry support to pybricks - a floating or docked window with data from the motors and sensors displayed. It’s the one nice feature in spike prime that pybricks is missing Add “file not saved’ indicator to pybricks  - put an asterisk after the file name if it’s been edited but  not saved to disk.    - display the name of the  connected hub in the guiBtw, code y’all bundle the web app with the firmware for the robots? Our FLL laptops can’t connect to the school wifi so upgrading  the robots requires taking them home