Docs: cleanups per JOSS review

[rkingsbury]

Numerous cleanups to the documentation.

• Fix rendering problems with math
• Fix rendering problems with equations ( Closes #55 )
• Document some previously undocumented class attributes
• Convert all docstrings to Google Format (Closes #54 )
• Closes #102

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 85.71429% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 80.52%. Comparing base (c43b2e6) to head (e481fc7).

Files	Patch %	Lines
src/pyEQL/equilibrium.py	0.00%	2 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #112 +/- ## ========================================== + Coverage 80.45% 80.52% +0.06% ========================================== Files 10 10 Lines 1448 1453 +5 Branches 251 251 ========================================== + Hits 1165 1170 +5 Misses 248 248 Partials 35 35 ```

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