Bugfix/linkchecker (#2)

* Fix broken documentation links in index.md

Change .md extensions to directory-style URLs:
- a2a-security/guides/scoring.md  scoring/
- capiscio-cli/scoring-system.md  scoring-system/

MkDocs converts .md files to directory URLs, so links must not include the .md extension.

Fixes: 404 errors in production link checker

* Fix broken documentation links

Remove .md extensions from documentation links to fix 404 errors.
MkDocs converts .md files to directory-style URLs.

Fixed links:
- support.md: concepts.md  concepts/, scoring-system.md  scoring-system/
- scoring-system.md: CLI and Python guide links
- index.md: a2a-security and CLI scoring links

Resolves production link checker failures.

Author: beonde