Add Community section to documentation

- Add new Community tab to docs navigation
- Create community showcase page for featuring high-quality projects
- Include example project (MCP Dummy Server) as initial content
- Add guidelines for community contributions
- Link to contrib modules in Further Reading section

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

docs/docs.json

@@ -150,6 +150,13 @@
                 "pages": [
                     "changelog"
                 ]
+            },
+            {
+                "anchor": "Community",
+                "icon": "users",
+                "pages": [
+                    "community/showcase"
+                ]
             }
         ]
     },