add pi-hole to portfolio (#21)

Co-authored-by: EdwardAngert <17991901+EdwardAngert@users.noreply.github.com>

Author: EdwardAngert

src/content/docs/portfolio/index.mdx

@@ -7,6 +7,8 @@ description: "Documentation samples across different organizations and project t
 import { LinkCard, CardGrid } from '@astrojs/starlight/components';
 
 <CardGrid>
+  <LinkCard title="Pi-hole v6 Documentation" href="/docs/pi-hole/" description="A personal documentation project that covers Pi-hole v6 installation and configuration, security hardening, DNS configuration, Tailscale integration, and troubleshooting. Written for my own deployment, it now draws 6,000+ unique visitors a month from around the world." />
+
   <LinkCard title="Coder Quickstart Documentation" href="/portfolio/coder-quickstart/" description="Created quickstart guide to unlock Coder for new users. Part of a broader information architecture effort to define user journeys and personas." />
 
   <LinkCard title="Work on a Contributor's PR in the Docs Repository" href="/portfolio/contrib-pr/" description="Created clear steps for technical writers working with external contributors, solving a recurring problem that was blocking the team." />