Add a description for each fileitemactionplugin class

fileitemactionplugin/syncthingdiractions.h

@@ -5,6 +5,9 @@
 
 #include "./syncthinginfoaction.h"
 
+/*!
+ * \brief The SyncthingDirActions class provides the read-only directory info actions.
+ */
 class SyncthingDirActions : public QObject {
     Q_OBJECT
     friend QList<QAction *> &operator<<(QList<QAction *> &, SyncthingDirActions &);

fileitemactionplugin/syncthingfileitemaction.h

@@ -7,6 +7,10 @@
 
 class KFileItemListProperties;
 
+/*!
+ * \brief The SyncthingFileItemAction class implements the plugin interface.
+ * \remarks This is the only class directly used by Dolphin.
+ */
 class SyncthingFileItemAction : public KAbstractFileItemActionPlugin {
     Q_OBJECT
 

fileitemactionplugin/syncthingfileitemactionstaticdata.h

@@ -3,6 +3,12 @@
 
 #include "../connector/syncthingconnection.h"
 
+/*!
+ * \brief The SyncthingFileItemActionStaticData class holds objects required during the whole application's live time.
+ *
+ * For instance the connection to Syncthing is kept alive until Dolphin is closed to prevent re-establishing it on each and
+ * every time the context menu is shown.
+ */
 class SyncthingFileItemActionStaticData : public QObject {
     Q_OBJECT
     Q_PROPERTY(QString configPath READ configPath)

fileitemactionplugin/syncthinginfoaction.h

@@ -8,6 +8,9 @@ QT_FORWARD_DECLARE_CLASS(QLabel)
 
 class SyncthingInfoAction;
 
+/*!
+ * \brief The SyncthingInfoWidget class displays a SyncthingInfoAction.
+ */
 class SyncthingInfoWidget : public QWidget {
     Q_OBJECT
 
@@ -23,6 +26,10 @@ private:
     QLabel *const m_iconLabel;
 };
 
+/*!
+ * \brief The SyncthingInfoAction class provides a display-only QAction used to show eg. the directory info.
+ * \remarks In contrast to a regular QAction, this class has no highlighting on mouseover event.
+ */
 class SyncthingInfoAction : public QWidgetAction {
     Q_OBJECT
 

fileitemactionplugin/syncthingmenuaction.h

@@ -9,6 +9,9 @@ namespace Data {
 enum class SyncthingStatus;
 }
 
+/*!
+ * \brief The SyncthingMenuAction class provides the top-level menu "Syncthing" entry for the context menu.
+ */
 class SyncthingMenuAction : public QAction {
     Q_OBJECT