fix: move initializing and installing of Dart docs to root of _supabase_dart

apps/reference/_supabase_dart/initializing.mdx

@@ -21,13 +21,13 @@ For `supabase_flutter`, you will be using the static `initialize()` method on `S
 
 ## Examples
 
-### Dart SupabaseClient()
+### Dart `SupabaseClient()`
 
 ```dart
 final supabase = SupabaseClient('https://xyzcompany.supabase.co', 'public-anon-key');
 ```
 
-### Flutter initialize()
+### Flutter `initialize()`
 
 ```dart title="main.dart"
 Future<void> main() async {

apps/reference/_supabase_dart/intro.mdx

@@ -27,4 +27,4 @@ You can use the `supabase-dart` library to:
 ## Additional Links
 
 - Source Code: [github.com/supabase/supabase-dart](https://github.com/supabase/supabase-dart)
-- [Known bugs and issues](https://github.com/supabase/supabase-dart/issues)
+- [Known bugs and issues](https://github.com/supabase/supabase-flutter/issues)

apps/reference/nav/supabase_dart_sidebars.js

@@ -6,7 +6,7 @@ const sidebars = {
     {
       type: 'category',
       label: 'Getting Started',
-      items: ['intro', 'generated/installing', 'generated/initializing'],
+      items: ['intro', 'installing', 'initializing'],
       collapsed: true,
     },
     {