add some documentation

lib/src/text_field/base_text_field.dart

@@ -118,6 +118,15 @@ class BaseTextFieldState extends State<BaseTextField>
   @visibleForTesting
   FocusNode get focusNode => _focusNode;
 
+  // We previous used the onChange event from the [TextFormField], since adding a listener to the [TextEditingController] is also called
+  // when we focus / unfocus the [TextFormField].
+  // 💾 This was the previous documentation:
+  // 💾 use onChange instead of [TextEditingController.addListener]
+  // 💾 because this will notify a text change when we loose focus
+  // 💾 when routing back. This will trigger a new search which is wrong.
+  // Since we now use the listener, we need to distinct the value by ourself.
+  late String _previousTextValue = widget.text;
+
   bool _textFieldIsValid = true;
 
   @override
@@ -241,6 +250,10 @@ class BaseTextFieldState extends State<BaseTextField>
   }
 
   void _onChanged(String value) {
+    if (_previousTextValue == value) return;
+
+    _previousTextValue = value;
+
     // we always want to validate the new input when the current state is invalid
     if (!_textFieldIsValid) {
       _formFieldKey.currentState?.validate();