Add wireguard dependency note

[kprosise]

PR Template and Checklist

Please complete as much as possible to speed up the reviewing process.

Readiness and adding reviewers as appropriate is required.

All PRs should be reviewed by a technical writer/documentation team and a peer. If effecting customers—which is a majority of content changes—a member of Customer Success must also review.

Readiness

• [x] Merge (pending reviews)
• [ ] Merge after date or event
• [ ] Draft

Overview

Adds a dependency reported by customer.

Checklist

• [x] Run spelling and grammar check, preferably with linter.
• [x] Avoid changing any header associated with a link/reference.
• [x] Step through instructions (or ask someone to do so).
• [x] Review for wordiness
• [x] Match tone and style of page/section.
• [x] Run make linkcheck.
• [x] View HTML in a browser to check rendering.
• [x] Use semantic newlines.
• [x] follow best practices for commits.
  • [x] Descriptive title written in the imperative.
  • [x] Include brief overview of QA steps taken.
  • [x] Mention any related issues numbers.
  • [x] End message with sign off/DCO line (-s, --signoff).
  • [x] Sign commit with your gpg key (-S, --gpg-sign).
  • [x] Squash commits if needed.
• [x] Request PR review by a technical writer and at least one peer.

[doanac]

Docs for 85aa42b60510a24f75b368955b0cf3b686af3b29 are browsable at: https://ci.foundries.io/projects/fio-docs/builds/2759/docs/artifacts/html/index.html