Incorrect Variable Naming in Examples - `PRIVATE_KEY` -> `GITHUB_PRIVATE_KEY` Leads to Error

[schlagelk]

What article on docs.github.com is affected?

https://docs.github.com/en/github-ae@latest/developers/apps/setting-up-your-development-environment-to-create-a-github-app

What part(s) of the article would you like to see updated?

There are two examples of .env files which currently reference a variable PRIVATE_KEY, when it should be GITHUB_PRIVATE_KEY. Using the incorrect variable name leads to an error when running template_server.rb

template_server.rb:34:in class:GHAapp': undefined method gsub' for nil:NilClass (NoMethodError)

Additional information

None

[welcome]

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