docs(demo/package-integritry/README.md): typo fix

[arthurlutz]

No description provided.

[jkowalleck]

Thank you very much for your contribution.
Please sign-off your commit -- see https://github.com/CycloneDX/cyclonedx-node-npm/blob/main/CONTRIBUTING.md#sign-off-your-commits

here is how to do this: https://github.com/CycloneDX/cyclonedx-node-npm/pull/1016/checks?check_run_id=15498614890
To add your Signed-off-by line to every commit in this branch:

1. Ensure you have a local copy of your branch by checking out the pull request locally via command line.
2. In your local branch, run: git rebase HEAD~1 --signoff
3. Force push your changes to overwrite the branch: git push --force-with-lease origin patch-1

[jkowalleck]

thank you for the contribution, @arthurlutz .
every bit is appreciated 🥇