archive(1.1) fix: update icon URLs based on virtual directory

[pepopowitz]

Note that this targets the unsupported/1.1 branch, and will not make it into main.

Description

Part of #2186.

Fixes the footer social icons in the unsupported/1.1 site.

The path to them is incorrect in these isolated sites, because they sit in a "virtual directory" named according to their version. So this one, for example, lives at unsupported.docs.camunda.io/1.1/. The footer icons are in the root in the main site, but here the path needs to be adjusted based on the /1.1/.

I'll update my automation changes from #2422 in a separate PR, so that I don't miss this on the next version archival.

When should this change go live?

• This change is not yet live and should not be merged until {ADD_DATE} (apply hold label or convert to draft PR)?
• There is no urgency with this change.
• This change or page is part of a marketing blog, conference talk, or something else on a schedule.
• This functionality is already available but undocumented.
• This is a bug fix or security concern.

PR Checklist

• I have added changes to the relevant /versioned_docs directory, or they are not for an already released version.
• I have added changes to the main /docs directory (aka /next/), or they are not for future versions.
• My changes require an Engineering review, and I've assigned an engineering manager or tech lead as a reviewer, or my changes do not require an Engineering review.
• My changes require a technical writer review, and I've assigned @christinaausley as a reviewer, or my changes do not require a technical writer review.

[pepopowitz]

merging this sans-approval since it's not a published site yet. Happy to make changes if you catch anything in review.