Qml/Main: add icon and action to placeholder

src/leek/qml/Main.qml

@@ -16,6 +16,7 @@ Kirigami.ApplicationWindow {
             Kirigami.Action {
                 // download-symbolic and install-symbolic are the same icon
                 // but install looks worse for some reason
+                id: addAction
                 icon.name: "download-symbolic"
                 text: "Add mod"
                 shortcut: StandardKey.New
@@ -84,10 +85,11 @@ Kirigami.ApplicationWindow {
 
             Kirigami.PlaceholderMessage {
                 anchors.centerIn: parent
-
+                icon.name: "edit-none"
                 visible: modsView.count === 0
                 text: "There's no mods installed"
                 explanation: "Install a mod, and it will show up here"
+                helpfulAction: addAction
             }
         }
     }