feat: improve fields documentation

Author: mdeandrea-mrmilu

lib/src/form_builder.dart

@@ -111,19 +111,23 @@ class FormBuilderState extends State<FormBuilder> {
 
   bool get enabled => widget.enabled;
 
-  /// Verify if all fields on form are valid
+  /// Verify if all fields on form are valid.
   bool get isValid => fields.values.every((field) => field.isValid);
 
-  /// Verify if some field on form are dirty
+  /// Will be true if some field on form are dirty.
+  ///
+  /// Dirty: The value of field is changed by user or by logic code.
   bool get isDirty => fields.values.any((field) => field.isDirty);
 
-  /// Verify if some field on form are touched
+  /// Will be true if some field on form are touched.
+  ///
+  /// Touched: The field is focused by user or by logic code.
   bool get isTouched => fields.values.any((field) => field.isTouched);
 
-  /// Get initialValue
+  /// Get initialValue.
   Map<String, dynamic> get initialValue => widget.initialValue;
 
-  /// Get all fields of form
+  /// Get all fields of form.
   FormBuilderFields get fields => _fields;
 
   Map<String, dynamic> get instantValue =>

lib/src/form_builder_field.dart

@@ -106,7 +106,15 @@ class FormBuilderFieldState<F extends FormBuilderField<T>, T>
 
   bool get enabled => widget.enabled && (_formBuilderState?.enabled ?? true);
   bool get _readOnly => !(_formBuilderState?.widget.skipDisabled ?? false);
+
+  /// Will be true if the field is dirty
+  ///
+  /// The value of field is changed by user or by logic code.
   bool get isDirty => _dirty;
+
+  /// Will be true if the field is touched
+  ///
+  /// The field is focused by user or by logic code
   bool get isTouched => _touched;
 
   InputDecoration get decoration => widget.decoration.copyWith(