Add `konnect_icon` support back

## Jobs to be done (optional)
I want to include icons for things in the UI that have no text label, currently including them as an tag or markdown image renders them incorrectly.

## Definition of done
Use Konnect icons like `{% konnect_icon runtimes %}` inline. I think these used this ruby file:

```
# frozen_string_literal: true

module Jekyll
class KonnectIconTag < Liquid::Tag
def initialize(tag_name, icon, tokens)
super
@icon = icon.strip
end

def render(_context)
"{:.inline .konnect-icn .no-image-expand}"
end
end
end

Liquid::Template.register_tag('konnect_icon', Jekyll::KonnectIconTag)
```

## Information

## Due date (optional)

## Size

Locate the Jekyll/Liquid tag registration and the existing Konnect icon assets under /assets/images/icons/konnect/. Start by checking how other custom tags are loaded, then restore the konnect_icon tag so `{% konnect_icon runtimes %}` renders the intended inline icon markup. Done means the syntax works in the documentation build without rendering the icon incorrectly.

Written by the indexing model from the issue text.