Updated documentation on export plugin

MacPass/MPPlugin.h

@@ -147,9 +147,32 @@ FOUNDATION_EXPORT NSString *const MPPluginDescriptionInfoDictionaryKey;
 @protocol MPExportPlugin <NSObject>
 
 @required
-
+/**
+ Called by the host to update a menu item for exporting.
+ You are supposed to update the title to something meaningfull.
+ Target and action will get set by host, so do not rely on them
+ 
+ @param item MenuItem that will be used to export via the plugin
+ */
 - (void)prepareExportMenuItem:(NSMenuItem *)item;
+
+/**
+ Called by the host when an export is about to happen.
+ Update the panel to work for all the files and formats you can export
+
+ @param panel The panel used to select the export destination
+ */
 - (void)prepareSavePanel:(NSSavePanel *)panel;
+/**
+ This will get called when the save panel is closed by the user.
+ You should retrieve any results from the panel and act accordingly.
+ 
+ If you need custom UI in the process, you can show them here.
+ For example, if a CSV export might need user input to configure its output this is the place to show it.
+ 
+ @param tree The current tree to be exported
+ @param panel The save panel that was used to specify the export destination
+ */
 - (void)exportTree:(KPKTree *)tree forRunningSavePanel:(NSSavePanel *)panel;
 
 @end