docs: Add mirai filled button documentation

website/docs/widgets/filled_button.md

@@ -0,0 +1,39 @@
+# Filled Button
+
+The Mirai Filled Button allows you to build a Flutter filled button widget using JSON.
+To know more about the filled button widget in Flutter, refer to the [official documentation](https://api.flutter.dev/flutter/material/FilledButton-class.html).
+
+## Properties
+
+| Property       | Type                    | Description                                                                        |
+|----------------|-------------------------|------------------------------------------------------------------------------------|
+| onPressed      | `Map<String, dynamic>?` | The callback that is called when the button is tapped.                             |
+| onLongPress    | `Map<String, dynamic>?` | The callback that is called when the button is long-pressed.                       |
+| onHover        | `Map<String, dynamic>?` | The callback that is called when the button is hovered over.                       |
+| onFocusChange  | `Map<String, dynamic>?` | The callback that is called when the button's focus changes.                       |
+| style          | `MiraiButtonStyle?`     | The style to apply to the button.                                                  |
+| autofocus      | `bool`                  | Whether the button should be focused when the page is loaded. Defaults to `false`. |
+| clipBehavior   | `Clip`                  | Determines how the content should be clipped. Defaults to `Clip.none`.             |
+| child          | `Map<String, dynamic>`  | The widget to display inside the button.                                           |
+
+## Example JSON
+
+```json
+{
+  "type": "filledButton",
+  "onPressed": {},
+  "onLongPress": {},
+  "onHover": {},
+  "onFocusChange": {},
+  "style": {
+    "backgroundColor": "#FFC107",
+    "foregroundColor": "#000000"
+  },
+  "autofocus": false,
+  "clipBehavior": "none",
+  "child": {
+    "type": "text",
+    "data": "Click Me!"
+  }
+}
+```