feat: Docs/code change for Gen 2 Firebase Functions

[AndrewLester]

Describe the problem

Gen 2 firebase functions require different imports and syntax in the functions/index.js file, which is seamless to edit and use with this library. That said, perhaps the content for the file, which is initially logged by the package, should use the gen 2 syntax. Alternatively, something could be added in the README to note the differences.

Describe the proposed solution

Something like the example in this file could be used:
https://github.com/AndrewLester/firebase-test/blob/main/functions/index.js

In addition, some note about making sure the function runs Node.js 18 would be helpful:
https://github.com/AndrewLester/firebase-test/blob/main/functions/package.json#L12

Alternatives considered

n/a

Importance

would make my life easier