Update redirect script to include hash anchors in URLs

[untra]

🔤 Polyglot PR

Implements #274 solution from @GruberMarkus for preserving anchor links in redirect in redirect.html

Adding + window.location.hash allows the client-side JavaScript redirect to correctly preserve and pass on any URL fragment identifier or anchor link that was present in the original URL.

Type of change

• Docs update (changes to the readme or a site page, no code changes)
• Ops wrangling (automation or test improvements)
• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Sweet release (needs a lot of work and effort)
• Something else (explain please)

Checklists

• If modifying code, at least one test has been added to the suite