Small fixes

[mcocdawc]

• use arctan(x, y) == arctan(x / r, y / r) for non-zero r and get rid of unnecessary division. Spotted by @nwhel
• added missing rst files for the new pyscf conversion methods.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

Project coverage is 0.00%. Comparing base (651ddc0) to head (0848851).

Files with missing lines	Patch %	Lines
...ord/_cartesian_coordinates/_cart_transformation.py	0.00%	1 Missing ⚠️
...oord/_cartesian_coordinates/_cartesian_class_io.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@          Coverage Diff           @@
##           master    #123   +/-   ##
======================================
  Coverage    0.00%   0.00%           
======================================
  Files          29      29           
  Lines        2761    2761           
======================================
  Misses       2761    2761           

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