Improve moments and spectrum_moments docstrings in particulator.py

[slayoo]

No description provided.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.47%. Comparing base (2bd8d58) to head (72917a3).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1947   +/-   ##
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  Coverage   87.47%   87.47%           
=======================================
  Files         430      430           
  Lines       11159    11159           
=======================================
  Hits         9761     9761           
  Misses       1398     1398           

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[Bodzio-2]

Missing a couple of } s and escaping the _ in attr_range

Corrected (checked in markdown and latex):
M_k = \frac{\left.\sum_i\right|_{\text{attr\_range[0]} < x_i < \text{attr\_range[1]} a_i^k m_i w_i^l}}{\left.\sum_i\right|_{\text{attr\_range[0]} < x_i < \text{attr\_range[1]} m_i w_i^l}}