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 PR on the cypress-testing-library (testing-library/cypress-testing-library#180))

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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[nickserv]

I agree with using the spelling TypeScript which is consistent with Microsoft's spelling, but why is the Egghead link changed? It seems like both links work but use different themes. Do they have a new backend?

[leschdom]

Hi @nickmccurdy

Thanks for reviewing my PR.
So the reason I wanted to change the link is, that it still looks "unofficial" - while technically the videos etc. seem to be available.

For example the link on top:
"We've got a new version of egghead in BETA. Click here to try it! ⚡️" . After clicking on it I come to https://egghead.io/courses/how-to-contribute-to-an-open-source-project-on-github.

So the page used to be in Beta some time ago, but is now the new official egghead.io Look&Feel.
To avoid confusion and one extra click I just directly point to the new link.

[codecov]

Codecov Report

Merging #932 (97b5a99) into main (6e6bf85) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##              main      #932   +/-   ##
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  Coverage   100.00%   100.00%           
=========================================
  Files            4         4           
  Lines          140       140           
  Branches        26        26           
=========================================
  Hits           140       140           

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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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