Documentation update and minor fixes

[ryanmphill]

This pull request makes several updates to improve documentation, package metadata, and project distribution. The main changes include updating the README.md for better clarity and PyPI installation instructions, removing the unused Pipfile, adding missing files to the package manifest, and bumping the package version.

Documentation and usage improvements:

• Updated README.md to:
  • Use PyPI badges and installation instructions instead of GitHub-based ones.
  • Clarify key features, installation, and usage steps.
  • Improve Jinja query examples and configuration documentation.
  • Simplify Netlify deployment instructions and clarify Python version requirements.
  • Refine development setup steps. [1] [2] [3] [4] [5] [6] [7] [8]

Packaging and distribution:

• Removed the unused Pipfile to clean up dependency management and avoid confusion.
• Added shodo_ssg/project_template/.gitignore to MANIFEST.in to ensure all necessary template files are included in package distributions.
• Bumped the package version in pyproject.toml from 0.0.dev3 to 0.0.dev4 to reflect these changes and prepare for a new release.