Add Caddy stripHTML fixed references

[cookesan]

Adds Caddy stripHTML fixed references to GHSA-vcc4-2c75-vc9v.

Audit refresh, July 8, 2026:

• Confirmed the live PR is open, ready for review, merge-clean, and the visible advisory check is green.
• Rechecked the merge-base diff: exactly one advisory JSON file changes (advisories/github-reviewed/2026/06/GHSA-vcc4-2c75-vc9v/GHSA-vcc4-2c75-vc9v.json), JSON parses, git diff --check passes, and the exact-head worktree is clean.
• Revalidated the added public references in the diff; all resolve through their source site or registry.

[cookesan]

Revalidated July 8, 2026: this remains scoped to Caddy stripHTML fixed evidence for GHSA-vcc4-2c75-vc9v. The Go module page, upstream PR, fix commit, and v2.11.4 tag resolve; affected ranges, severity, and advisory metadata remain unchanged. Local merge-base checks pass with a single advisory JSON file changed, JSON parsing, git diff --check, and a clean worktree.