GH-4643 fix docgen description displaying for info addon

[MihaChicken]

Issue: #4643

What I did

1. Fix lookup for docgen description to look for component name(story.kind) instead of story name
2. Add some tests to cover this usecase

[storybook-safe-bot]

	Fails
🚫	PR is not labeled with one of: ["cleanup","BREAKING CHANGE","feature request","bug","documentation","maintenance","dependencies:update","dependencies","other"]

Generated by 🚫 dangerJS

[codecov]

Codecov Report

Merging #4685 into master will increase coverage by 0.16%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #4685      +/-   ##
==========================================
+ Coverage   35.59%   35.75%   +0.16%     
==========================================
  Files         557      557              
  Lines        6732     6732              
  Branches      884      884              
==========================================
+ Hits         2396     2407      +11     
+ Misses       3876     3866      -10     
+ Partials      460      459       -1

Impacted Files	Coverage Δ
addons/info/src/components/Story.js	88.88% <100%> (+11.11%)	⬆️

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[MihaChicken]

@danielduan thank you for reviewing my pull request.
Could you please tell me when it could be merged?

[shilman]

Sorry I broke the build. I've committed updated snapshots to fix it but it looks like the circle's docker server is down ... hope this will get sorted out soon. 🙇