Broken default fallback URL in community-lists shortcode resulting in 404 links

Problem

In layouts/_shortcodes/community-lists.md, line 2 configures the fallback URL for contribution guidelines when .Page.Params.contributingUrl is omitted from page front-matter:

{{ $contribUrl := .Page.Params.contributingUrl | default "docs/contribution-guidelines" -}}

However, docs/contribution-guidelines does not exist in the site repository. The actual contribution documentation page is located at content/en/docs/contributing.md (which renders to /docs/contributing/).

Root Cause

1. Line 2 of layouts/_shortcodes/community-lists.md hardcodes "docs/contribution-guidelines" as the default fallback parameter.
2. The site documentation structure uses /docs/contributing/ for contribution guidelines.
3. If the contributingUrl front-matter parameter is omitted or removed from a page rendering the {{% community-lists %}} shortcode, the shortcode generates a link to /docs/contribution-guidelines/, which returns a 404 Not Found error.

Affected Components

• layouts/_shortcodes/community-lists.md

Reproduction / Evidence

1. Inspect layouts/_shortcodes/community-lists.md line 2 and line 23:

   {{ $contribUrl := .Page.Params.contributingUrl | default "docs/contribution-guidelines" -}}
   ...
   [{{ T "community_guideline" }}]({{ $contribUrl | relURL }}).
   

2. Note that git ls-files content/en/docs/ contains content/en/docs/contributing.md (rendered at /docs/contributing/), while /docs/contribution-guidelines does not exist.

Acceptance Criteria

• Update the default fallback URL in layouts/_shortcodes/community-lists.md from "docs/contribution-guidelines" to "/docs/contributing/".
• Verify that community-lists renders valid, resolving links to the Contributing page even when contributingUrl is omitted from front matter.

Proposed Solution Direction

Update line 2 of layouts/_shortcodes/community-lists.md to fallback to "/docs/contributing/":

{{ $contribUrl := .Page.Params.contributingUrl | default "/docs/contributing/" -}}

Open layouts/_shortcodes/community-lists.md and inspect the fallback URL on line 2 and its use on line 23. Update the fallback to the documented /docs/contributing/ path, then render the community-lists shortcode without contributingUrl and verify that the generated link resolves to the Contributing page.