Documentation of model parameters

[jdebacker]

This PR adds utilities to generate a chapter of the OG-Core documentation that describes each model parameter using metadata from default_parameters.py. Github Actions are updated to ensure this page is regenerated and compiled with the documentation at each PR.

View of the new chapter:

[jdebacker]

Relates to Issue #954

[jdebacker]

Also addes rst file for pension model API, addressing Issue #953

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 10.52632% with 17 lines in your changes missing coverage. Please review.

Project coverage is 71.07%. Comparing base (e799452) to head (2f66a35).
Report is 2 commits behind head on master.

Files	Patch %	Lines
ogcore/utils.py	10.52%	17 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #963      +/-   ##
==========================================
- Coverage   71.31%   71.07%   -0.24%     
==========================================
  Files          20       20              
  Lines        4953     4972      +19     
==========================================
+ Hits         3532     3534       +2     
- Misses       1421     1438      +17     

Flag	Coverage Δ
unittests	71.07% <10.52%> (-0.24%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
ogcore/utils.py	84.13% <10.52%> (-3.05%)	⬇️

[rickecon]

@jdebacker. This is such a cool addition to the documentation. Merging.