Update the JavaScript SDK Quickstart

[feorlen]

Some small updates so the text better matches Docs style, since this README is imported directly into the web docs.

I made a few changes to the example also, like make it work if the bucket exists. I'm not a great JavaScript person so please let me know the usual style so it makes sense.

I was able to run the example with the latest Node.js, seems like it requires at least v 16. Is that accurate? When I tried with v12.22.9 I got required: { node: '^16 || ^18 || >=20' }.

Corresponding Docs issue minio/docs#1042

[prakashsvmx]

We focus on supporting node LTS versions. https://nodejs.org/en/about/previous-releases @feorlen .

[trim21]

in fact it support down to node v12

[feorlen]

Finally able to get back to this, it's become a lower priority task for other reasons. But I still need to know something about JS for future work, so worth getting right. Appreciate any additional comments.

[feorlen]

Updated the file-uploader.mjs example in the README, although I don't know where to see the linter's issue with it. The check detail doesn't say.

Are there still needed changes in the examples dir?

[aldy505]

@feorlen formatter check is failing, you should do npm run format

[aldy505]

The changes looks good to me.

Pinging @trim21 @prakashsvmx @kaankabalak for review.

[feorlen]

Looks like I installed prettier correctly yay. One small fix, update branch, maybe this is good now. 🎉

Appreciate the guidance getting through this!