Adds comments explaining currency setting storage

Author: Ecarrion

WooCommerce/Classes/Tools/Shared Site Settings/SelectedSiteSettings.swift

@@ -63,6 +63,7 @@ extension SelectedSiteSettings {
             ServiceLocator.currencySettings.updateCurrencyOptions(with: $0)
         }
 
+        // Needed to correcly format the widget data.
         UserDefaults.group?[.defaultStoreCurrencySettings] = try? JSONEncoder().encode(ServiceLocator.currencySettings)
     }
 }

WooCommerce/Classes/Yosemite/DefaultStoresManager.swift

@@ -511,6 +511,8 @@ private extension DefaultStoresManager {
         UserDefaults.group?[.defaultStoreID] = siteID
         UserDefaults.group?[.defaultStoreName] = sessionManager.defaultSite?.name
 
+        // Currency Settings are stored in `SelectedSiteSettings.defaultStoreCurrencySettings`
+
         // Reload widgets UI
         WidgetCenter.shared.reloadAllTimelines()
     }