Fix broken links in MDX documentation files

Removed incorrect /docs/ prefix and .md extensions from internal links in MDX files:
- plugin-editor.mdx: Fixed /docs/concepts/plugins → /concepts/plugins
- plugin-kanban.mdx: Fixed /docs/concepts/plugins → /concepts/plugins
- plugin-markdown.mdx: Fixed /api → /reference/api, /docs/concepts/plugins → /concepts/plugins
- plugin-markdown.mdx: Fixed CONTRIBUTING.md → GitHub URL
- plugin-object.mdx: Fixed /docs/ prefixes and removed .md extensions
- navigation-menu.mdx: Fixed example hrefs from /docs/intro → /intro, etc.

All MDX files now use correct fumadocs link format without /docs/ prefix.

Co-authored-by: xuyushun441-sys <255036401+xuyushun441-sys@users.noreply.github.com>

Author: Copilot

docs/components/basic/navigation-menu.mdx

@@ -50,17 +50,17 @@ The Navigation Menu component provides an accessible menu for site navigation.
           {
             label: 'Introduction',
             description: 'Learn the basics',
-            href: '/docs/intro'
+            href: '/intro'
           },
           {
             label: 'Installation',
             description: 'Install the package',
-            href: '/docs/install'
+            href: '/install'
           },
           {
             label: 'Quick Start',
             description: 'Build your first app',
-            href: '/docs/quick-start'
+            href: '/quick-start'
           }
         ]
       }

docs/plugins/plugin-editor.mdx

@@ -178,6 +178,6 @@ const editorSchema: CodeEditorSchema = {
 
 ## Related Documentation
 
-- [Plugin System Overview](/docs/concepts/plugins)
+- [Plugin System Overview](/concepts/plugins)
 - [Lazy-Loaded Plugins Architecture](../concepts/lazy-loading)
 - [Package README](https://github.com/objectstack-ai/objectui/tree/main/packages/plugin-editor)

docs/plugins/plugin-kanban.mdx

@@ -422,6 +422,6 @@ const kanbanSchema: KanbanSchema = {
 
 ## Related Documentation
 
-- [Plugin System Overview](/docs/concepts/plugins)
+- [Plugin System Overview](/concepts/plugins)
 - [Lazy-Loaded Plugins Architecture](../concepts/lazy-loading)
 - [Package README](https://github.com/objectstack-ai/objectui/tree/main/packages/plugin-kanban)

docs/plugins/plugin-markdown.mdx

@@ -189,7 +189,7 @@ npm install our-package
 2. Configure your settings
 3. Start building!
 
-For more information, see the [API Reference](/api).
+For more information, see the [API Reference](/reference/api).
   `,
   className: 'prose prose-lg max-w-none'
 }
@@ -230,7 +230,7 @@ app.run()
 
 ## Contributing
 
-Contributions are welcome! Please read our [contributing guidelines](CONTRIBUTING.md).
+Contributions are welcome! Please read our [contributing guidelines](https://github.com/objectstack-ai/objectui/blob/main/CONTRIBUTING.md).
 
 ## License
 
@@ -376,6 +376,6 @@ const markdownSchema: MarkdownSchema = {
 
 ## Related Documentation
 
-- [Plugin System Overview](/docs/concepts/plugins)
+- [Plugin System Overview](/concepts/plugins)
 - [Lazy-Loaded Plugins Architecture](../concepts/lazy-loading)
 - [Package README](https://github.com/objectstack-ai/objectui/tree/main/packages/plugin-markdown)

docs/plugins/plugin-object.mdx

@@ -539,7 +539,7 @@ const dataSource = new ObjectQLDataSource({
 
 ## Related Documentation
 
-- [ObjectQL Integration](/docs/ecosystem/objectql.md)
-- [Data Sources](/docs/concepts/data-source.md)
-- [Plugin System Overview](/docs/concepts/plugins)
+- [ObjectQL Integration](/ecosystem/objectql)
+- [Data Sources](/concepts/data-source)
+- [Plugin System Overview](/concepts/plugins)
 - [Package README](https://github.com/objectstack-ai/objectui/tree/main/packages/plugin-object)