Adds wsl install note to CONTRIBUTING.md

[isaiah3031]

Read comments, before committing pull request read checklist again

Checklist:

• I have performed a self-review of my own code,

• I have commented my code, particularly in hard-to-understand areas,

• I have made corresponding changes to the documentation,

• I have added tests that prove my fix is effective or that my feature works,

• New and existing unit tests pass locally with my changes ("bundle exec rake"),

• Title include "WIP" if work is in progress.

Description

Guide questions:

• What motivated this change (if not already described in an issue)? There was a request for a way to run Linux on a windows machine in the CONTRIBUTING.md file
• What alternative solutions did you consider? WSL-2 is a "lightweight utility virtual machine (VM)". An alternative would be running an actual virtual machine or using a docker container.
• What are the tradeoffs for your solution? Lacks the full features of Linux and can be less performant. List any dependencies that are required for this change. (gems, js libraries, etc.)

Include anything else we should know about.

Type of change

• Documentation update