Add doc segments

[mathialo]

These are taken from the DB extractor, but I imagine they can be useful for other extractors. If we put them here, we can load them while creating docs the same way we reuse config schemas

[codecov]

Codecov Report

Merging #285 (13d8f01) into master (fa35383) will decrease coverage by 0.03%.
The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #285      +/-   ##
==========================================
- Coverage   78.75%   78.72%   -0.03%     
==========================================
  Files          22       22              
  Lines        1972     1974       +2     
==========================================
+ Hits         1553     1554       +1     
- Misses        419      420       +1     

see 2 files with indirect coverage changes