docs: clarify installation steps and add Windows test instructions

[saun09]

Pull Request

Description

This PR updates the development installation guide in the README to improve the onboarding experience, specifically for Windows users.

Motivation:
While setting up my local environment, I encountered a ModuleNotFoundError for dask and pathing issues with the global pytest command. This update clarifies the setup process and ensures new contributors can get the test suite running quickly.

Changes:

• Added explicit steps for cloning and virtual environment setup.
• Added a troubleshooting step for pip install dask[complete].
• Recommended using python -m pytest to ensure the local environment's dependencies are used.

How Has This Been Tested?

I followed the updated instructions on a Windows 11 machine within a fresh virtual environment.

• Successfully installed dependencies using pip install -e ".[dev]".

• Verified that dask was correctly recognized after the troubleshooting step.

• Ran the full test suite using python -m pytest.

• Yes (Verified 82 tests passed)

If your changes affect data processing, have you plotted any changes?

• N/A (Documentation change only)

Checklist:

• My code follows OCF's coding style guidelines
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• I have added tests (N/A for documentation)
• I have checked my code and corrected any misspellings