Optionally show headings and error message

[srevinsaju]

ASLOv4 always showed 'no description found' message whenever description / changelog / new in this feature was missing or failed to parse. In such cases, it was better to not show the message and hide that section. Improves accessibility

Fixes #27

[codecov]

Codecov Report

Merging #31 into master will increase coverage by 0.02%.
The diff coverage is 41.66%.

@@            Coverage Diff             @@
##           master      #31      +/-   ##
==========================================
+ Coverage   31.30%   31.33%   +0.02%     
==========================================
  Files           8        8              
  Lines         674      683       +9     
==========================================
+ Hits          211      214       +3     
- Misses        463      469       +6     

Impacted Files	Coverage Δ
aslo4/generator.py	29.02% <12.50%> (-0.56%)	⬇️
aslo4/constants.py	100.00% <100.00%> (ø)

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