doc: add preveen-stack to triagers

I have been contributing nodejs ecosystem over the last few years

• contributions to help issues:

  • through preveen-stack handle:

    • https://github.com/nodejs/help/issues?q=is%3Aissue+commenter%3Apreveen-stack

  • through wide4head handle:

    • https://github.com/nodejs/help/issues?q=is%3Aissue+commenter%3Awide4head

  • contributions to nodejs/help:

    • https://github.com/nodejs/help/pulls?q=is%3Apr+author%3Apreveen-stack

• contributions to core:

  • https://github.com/nodejs/node/issues?q=is%3Aissue+commenter%3Apreveen-stack
  • https://github.com/nodejs/node/pulls?q=is%3Apr+author%3Awide4head

I would like to get more involved and am looking forward to becoming a contributor

I have read through nodejs code of conduct and promise to adhere to the same 🙏🏽