added reciprocity description

lib/l10n/intl_en.arb

@@ -43,6 +43,7 @@
     "film": "Film",
     "filmPush": "Film (push)",
     "filmPull": "Film (pull)",
+    "filmReciprocityHint": "Applies correction for shutter speeds grater than 1 second",
     "equipment": "Equipment",
     "equipmentProfileName": "Equipment profile name",
     "equipmentProfileNameHint": "Praktica MTL5B",

lib/l10n/intl_fr.arb

@@ -43,6 +43,7 @@
     "film": "Pellicule",
     "filmPush": "Pellicule (push)",
     "filmPull": "Pellicule (pull)",
+    "filmReciprocityHint": "La correction s'applique aux vitesses d'obturation supérieures à 1 seconde",
     "equipment": "Équipement",
     "equipmentProfileName": "Nom du profil de l'équipement",
     "equipmentProfileNameHint": "Praktica MTL5B",

lib/l10n/intl_ru.arb

@@ -43,6 +43,7 @@
     "film": "Пленка",
     "filmPush": "Пленка (push)",
     "filmPull": "Пленка (pull)",
+    "filmReciprocityHint": "Применяет коррекцию для выдержек длиннее 1 секунды",
     "equipment": "Оборудование",
     "equipmentProfileName": "Название профиля",
     "equipmentProfileNameHint": "Praktica MTL5B",

lib/l10n/intl_zh.arb

@@ -43,6 +43,7 @@
     "film": "胶片",
     "filmPush": "胶片 (push)",
     "filmPull": "胶片 (pull)",
+    "filmReciprocityHint": "Applies correction for shutter speeds grater than 1 second",
     "equipment": "设备",
     "equipmentProfileName": "设备配置名称",
     "equipmentProfileNameHint": "Praktica MTL5B",

lib/screens/metering/components/shared/readings_container/components/film_picker/widget_picker_film.dart

@@ -15,6 +15,7 @@ class FilmPicker extends StatelessWidget {
     return AnimatedDialogPicker<Film>(
       icon: Icons.camera_roll,
       title: S.of(context).film,
+      subtitle: S.of(context).filmReciprocityHint,
       selectedValue: Films.selectedOf(context),
       values: Films.inUseOf(context),
       itemTitleBuilder: (_, value) => Text(value.name.isEmpty ? S.of(context).none : value.name),