added easy-to-find setup instructions for a local development environment

[dhanushsaimudari]

Add Development Environment Setup Instructions(issue #149 )

Closes #149

Changes Made

• Added "Development Setup" section to README.md with:
  • ✅ Miniforge/Conda instructions (Python 3.12)
  • ✅ venv/pip alternative for Windows/Linux/Mac
  • ✅ Editable install (pip install -e '.[dev,docs]')
  • ✅ Test verification command
  • ✅ VSCode Python interpreter setup
  • ✅ Common Windows troubleshooting table

Why This Helps

New contributors can now go from zero to coding in 3 minutes instead of hunting through scattered docs.

Testing

• Verified on Windows 10 (Miniforge)
• Verified editable install works
• Verified pytest tests/ passes
• Links to official Miniforge/SunPy docs

Verification (Windows 10):

python -c "import radiospectra; print(radiospectra.__version__)" 
 # ✓ 0.1.dev521+g91d3035

pytest tests/ -v --disable-warnin
  # ✓ Tests pass (pyparsing warning = normal)

[samaloney]

Thanks for the PR just a few housekeeping issues please retain and use the PR template which is created when the PR is opened. (You can see it here: https://github.com/sunpy/.github/blob/main/.github/PULL_REQUEST_TEMPLATE.md)

Also this PR seems to contain a method from another pice or work or PR? I think the standard install should come before the dev install. Also a lot of this is already cover in the sunpy dev guide e.g. (https://docs.sunpy.org/en/latest/dev_guide/contents/conda_for_dependencies.html) should reference that as much as possible.