Fix spelling of "Gatsby" :)

[papandreou]

It shouldn't really be necessary, but because of @gatsbot's insistence I'll elaborate :)

Background

• The name of the Gatsby project is hard to spell when you're in a hurry, possibly because of the three consecutive consonants
• There are several cases of funny misspellings of Gatsby on gatsby.org

Motivation

It's nicer to read texts that don't have too many spelling mistakes

What this change does

Corrects two misspellings of Gatsby in one document.

Possible follow-ups

I suggest doing a sweep through all the documentation and website. Maybe @gatsbot could be taught to recognize the common misspellings so it could give actually useful feedback on PRs? 😼

[gatsbot]

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[m-allanson]

Thanks for the thorough issue description 😄

[gatsbot]

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