docs(vite-legacy): Note about using regenerator-runtime in Content Security Policy environment

[svilen-ivanov]

Description

Can't use regenerator-runtime with CSP on old browsers (e.g. Chrome 38, IE 11). Caused by lack of globalThis and resorting to dynamic eval. Add documentation how to workaround it.

Additional context

I encounter this problem while migrating to Vite. I'd like to update the documentation for giving other users heads up. Here is the relevant regenrator-runtime fragment, and different attempt to fix it

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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