Remove elements that don't appear necessary

[tsalo]

Closes none.

Changes proposed in this pull request

• Update my affiliation in the .zenodo.json.
  • Should we switch to CITATION.cff/datacite.yml?
• Remove files that appear unnecessary: _version.pyi, __main__.py, and click code in cli/__init__.py.
• Remove submodule from .gitmodules. I know we'll want to use submodules to wrangle test data, but I don't want to put the cart before the horse.
• Add a little info on how to customize the template in the README. Plus I thought it would be nice to have recommendations in place for citing the template.
• Make heading format consistent in docs, based on https://www.sphinx-doc.org/en/master/usage/restructuredtext/basics.html#sections.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 26.36%. Comparing base (73ac4a3) to head (e2aca7d).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #10      +/-   ##
==========================================
+ Coverage   26.21%   26.36%   +0.14%     
==========================================
  Files          17       19       +2     
  Lines        1358     1358              
  Branches      202      202              
==========================================
+ Hits          356      358       +2     
+ Misses        992      990       -2     
  Partials       10       10              

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