[Improvement] Local Development Setup Documentation (especially for Windows)

Description:

The current local development setup instructions can be confusing for new contributors, particularly on Windows. Many contributors report difficulties with installing dependencies, resolving build errors, and understanding the correct tooling setup (Node/Yarn/MongoDB/Meteor) when trying to run Rocket.Chat locally.

What could be improved:

1. Add a clear Windows-verified step-by-step setup guide (including versions and required tooling).

2. Add a troubleshooting section for common errors during dependency installation and build steps.

3. Clarify when to use Docker vs native Meteor setup.

4. Include example .env setup and common fixes for build failures.

Why this matters:

A better onboarding experience will reduce setup issues for first-time contributors and improve contributor retention.

I am willing to:

1. Implement documentation changes

2. Test on Windows 10/11

3. Iterate based on maintainer feedback

4. Add screenshots or short gifs if needed

( This is being raised as a clarification / improvement request.
If a detailed and up-to-date contribution guide for local setup (especially for Windows) already exists, please confirm and point to it. )

Start by locating the existing local development and contribution setup documentation, then compare its Node, Yarn, MongoDB, and Meteor instructions with a Windows 10/11 setup. Check both Docker and native Meteor paths, record dependency and build errors, and document verified steps, troubleshooting guidance, and example environment configuration.