Add hello world to quickstart

[mintlify]

Added "hello world" to the top of the quickstart.mdx file.

Commands used

git checkout -b add-hello-world-quickstart
git add quickstart.mdx
git commit -m "Add hello world to quickstart"
gh api -X POST /repos/mintlify/docs/git/blobs --input blob-content.json
gh api -X POST /repos/mintlify/docs/git/trees --input tree-payload.json
gh api -X POST /repos/mintlify/docs/git/commits --input commit-payload.json
gh api -X POST /repos/mintlify/docs/git/refs --input ref-payload.json
gh api -X PATCH /repos/mintlify/docs/git/refs/heads/add-hello-world-quickstart --input ref-update-payload.json
gh api -X POST /repos/mintlify/docs/pulls --input pr-payload.json

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

^{Bugbot Autofix is OFF. To automatically fix reported issues with Cloud Agents, enable Autofix in the Cursor dashboard.}

[cursor]

Test content added to production documentation

Medium Severity

The text Hello world! appears to be test content added to production documentation. The quickstart guide is about deploying documentation sites, and this placeholder text doesn't serve any documentation purpose. The PR description containing "Instructions for Creating PRs in Future" suggests this was a demonstration or test PR that accidentally includes non-production content. If merged, users would see this random greeting in the quickstart documentation.