adopt shopyo contribution guide and add troubleshooting section

[taa-nguyen]

Add contribution instructions and a troubleshooting section

Adopted the Shopyo contribution instructions to work for ShopCube. Addressed the issue raised here.

Description

Borrowed from the Shopyo contribution docs and adopted them to work for ShopCube. Added a troubleshooting section based on my own issues setting up ShopCube for the first time and the issues that came up in community discord.

Motivation and Context

Motivation for this fix was to help fellow newcomers to ShopCube get the ShopCube app running locally on their machines. The hope is to make contributors feel welcome and easily onboarded to the project.

Screenshots (if appropriate):

An example of a common newcomer issue that is solved by updating contributing.md:

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Chore (improves application but is not new functionality nor a bug fix)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[rehmanis]

@taa-nguyen looks good. I tried and was able to follow the setup instructions. I was thinking should we move this to READMEmd since at the moment the README.md is quite empty. Maybe even replace the setup instructions there with this? @Abdur-rahmaanJ what do you think?

[Abdur-rahmaanJ]

Lol cool OR, yes looks good!