Region docs

[sjsrey]

Partially address #173.

Doesn't touch skater.

[codecov]

Codecov Report

Merging #214 (0b289ba) into main (863f40b) will increase coverage by 0.3%.
The diff coverage is 100.0%.

@@           Coverage Diff           @@
##            main    #214     +/-   ##
=======================================
+ Coverage   65.2%   65.5%   +0.3%     
=======================================
  Files         23      23             
  Lines       2462    2466      +4     
  Branches     535     535             
=======================================
+ Hits        1605    1614      +9     
+ Misses       783     774      -9     
- Partials      74      78      +4     

Impacted Files	Coverage Δ
spopt/region/azp_util.py	36.3% <ø> (ø)
spopt/region/maxp.py	96.0% <100.0%> (+<0.1%)	⬆️
spopt/region/region_k_means.py	97.4% <100.0%> (+0.1%)	⬆️
spopt/_version.py	33.8% <0.0%> (+1.5%)	⬆️