Update examples

[melroy89]

The current examples are like 11 years old. I expect there are better more up to date examples, which also show the mysql2/promise as well.

I'm referring to this documentation page: https://sidorares.github.io/node-mysql2/docs/examples. Which has very outdated examples IMO.

[wellwelwel]

Hey, @melroy89 🙋🏻‍♂️

When migrating the docs to the website, I din't touch those examples from "Introduction" section, even the deprecated ones.

What examples do you think would be good to show in the Introduction section?

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On sidebar, there are some already existing and new examples, including some usage variations for MySQL2 features: