Fix typo in yarn example

[hegelocampus]

Very Minor typo fix.
Changes yarn create react-app ... to yarn create-react-app ...
Fixes #8395

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[amyrlam]

Hi @hegelocampus - thanks for the PR! It's confusing but it's not a typo, check out this webpage: https://legacy.yarnpkg.com/en/docs/cli/create/.

If you use npx it's npx create-react-app my-app though. Ref: https://create-react-app.dev/docs/getting-started#npx

Hope this helps! cc @oluoluoxenfree