Add module docstrings

[kelly-sovacool]

Changes

Add minimal module docstrings

Also move template-related functions to the templates module

Issues

NA

PR Checklist

(~Strikethrough~ any points that are not applicable.)

• [x] This comment contains a description of changes with justifications, with any relevant issues linked.
• [x] Write unit tests for any new features, bug fixes, or other code changes.
• [x] Update docs if there are any API changes.
• [x] Update CHANGELOG.md with a short description of any user-facing changes and reference the PR number. Guidelines: https://keepachangelog.com/en/1.1.0/

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 29.92%. Comparing base (9725718) to head (e27b9c0). Report is 9 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #12 +/- ## ========================================== - Coverage 35.37% 29.92% -5.46% ========================================== Files 13 17 +4 Lines 1046 1260 +214 ========================================== + Hits 370 377 +7 - Misses 676 883 +207 ```

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