docs(CONTRIBUTING): update links

[leschdom]

What:
Update links (e.g. egghead.io link redirects to some old preview page for their newly launched site).
Renamed Typescript to TypeScript
(As I did with my first PRs on the cypress-testing-library and react-testing-library)

Why:
It could be confusing for first-time contributors (egghead.io links)
It gives a even more professional look when the naming of tools etc. is spelled correctly (at least to me 😅)

How:
Searched for the correct links:
OLD: https://egghead.io/series/how-to-contribute-to-an-open-source-project-on-github
NEW: https://egghead.io/courses/how-to-contribute-to-an-open-source-project-on-github

Have found a source to link why I would like to update the TypeScript spelling:
https://effectivetypescript.com/2021/02/03/pet-peeves/

Checklist:

• Documentation added to the
  docs site N/A
• Tests N/A
• Typescript definitions updated N/A
• Ready to be merged
  

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[codecov]

Codecov Report

Merging #977 (2a88c2d) into main (75197fe) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##              main      #977   +/-   ##
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  Coverage   100.00%   100.00%           
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  Files           25        25           
  Lines          914       914           
  Branches       283       283           
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  Hits           914       914           

Flag	Coverage Δ
node-12	100.00% <ø> (ø)
node-14	100.00% <ø> (ø)
node-16	100.00% <ø> (ø)

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[nickserv]

@all-contributors add @leschdom for docs

[allcontributors]

@nickmccurdy

I've put up a pull request to add @leschdom! 🎉

[github-actions]

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