Langevin docs update

[crisbutu]

Description

Made two updates to the documentation related to rotational motion with Langevin dynamics:

1. redefined L as angular velocity instead of angular momentum
2. changed the units of gamma_r from time^-1 to mass * length^2 * time^(-1)

Motivation and context

Resolves #1768

How has this been tested?

Manually made sure the latex changes parsed correctly by pasting them into an online latex editor.

Change log

Checklist:

• I have reviewed the Contributor Guidelines.
• I agree with the terms of the HOOMD-blue Contributor Agreement.
• My name is on the list of contributors (sphinx-doc/credits.rst) in the pull request source branch.

[tommy-waltmann]

Thanks for the PR, we always like it when external folks contribute fixes!

One more thing for discussion: if $\vec L$ is actually the angular velocity, should we change the variable in the docstring to be $\vec \omega$ so its consistent with standard variable naming conventions?

[crisbutu]

@tommy-waltmann I addressed the comments and this is ready for another look!

[tommy-waltmann]

pre-commit.ci autofix

[tommy-waltmann]

This looks good, we now just need to satisfy the code and documentation style enforced by pre-commit. A list of lines that need fixing is included here: https://results.pre-commit.ci/run/github/147663007/1714140577.QTa6j2IcTPmDJO5n3xovrg .

[joaander]

You can get fixes for:

hoomd/simulation.py:560:45: E226 missing whitespace around arithmetic operator
sphinx-doc/conf.py:63:21: E201 whitespace after '{'
sphinx-doc/conf.py:63:26: E202 whitespace before '}'

by merging the upstream trunk-patch into your branch.

[crisbutu]

@tommy-waltmann pre-commit now passes

[tommy-waltmann]

Thanks for the fix!