fix word typo in readme

README.md

@@ -36,7 +36,7 @@ Pub: [FlutterQuill]
   - [Demo](#demo)
   - [Installation](#installation)
   - [Usage](#usage)
-  - [Mirgration](#mirgration)
+  - [Migration](#migration)
   - [Input / Output](#input--output)
   - [Configurations](#configurations)
     - [Using Custom App Widget](#using-custom-app-widget)
@@ -133,8 +133,8 @@ And depending on your use case, you might want to dispose the `_controller` in d
 
 Check out [Sample Page] for more advanced usage.
 
-## Mirgration
+## Migration
-We have recently add [mirgration guide](/doc/migration.md) for mirgration from different versions
+We have recently add [migration guide](/doc/migration.md) for migration from different versions
 
 ## Input / Output