(IGNORE) Update README.md

[crandmck]

Made header levels consistent, and some minor grammar, spelling, formatting and punctuation corrections.

Changes in this pull request

Improvements to the README.

Checklist

• [x] This PR represents a single feature, fix, or change.
• [x] All applicable changes have been documented.
• [x] Any TO DO items (or similar) have been entered as GitHub issues and the link to that issue has been included in a comment.

[codecov-commenter]

Codecov Report

Merging #131 (8e7c0fa) into main (33fce98) will not change coverage. The diff coverage is n/a.

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@@           Coverage Diff           @@
##             main     #131   +/-   ##
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  Coverage   83.91%   83.91%           
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  Files           3        3           
  Lines         373      373           
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  Hits          313      313           
  Misses         60       60