Update babel for generating docs

[imurchie]

Proposed changes

We use babel-node to generate docs from yaml. Update this infrastructure.

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• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

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• I have added tests that prove my fix is effective or that my feature works
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[imurchie]

Update: we do all the transpilation anyway. So just add the docs generation scripts to the transpilation sources, and adjust the paths so the scripts work in ./build.

Then the package only needs to import @babel/runtime like any other Appium package.