docs: add CONTRIBUTING in docs

docs/.vitepress/config.ts

@@ -154,11 +154,20 @@ export default defineConfig({
             link: "/changelog/3.0",
           },
           {
-            text: "2.6 更新日志",
+            text: "2.6 更新说明",
             link: "/changelog/2.6",
           },
         ],
       },
+      {
+        text: "开发者文档",
+        items: [
+            {
+                text: "贡献指南",
+                link: "/dev/",
+            },
+        ]
+      }
     ],
   },
 });

docs/dev/index.md

@@ -0,0 +1 @@
+CONTRIBUTING.md