Enabled the paper menu entry in the Help window

It has also been slightly renamed...

src/gui/HelpWindow.cc

@@ -132,10 +132,9 @@ void HelpWindow::createMenu()
 	menu_view->addAction(view_file_bugreport_);
 	connect(view_file_bugreport_, &QAction::triggered,
 		[]{ QDesktopServices::openUrl(QUrl("https://gitlabext.wsl.ch/snow-models/inishell/-/issues")); });
-	auto *show_paper = new QAction(tr("Show &paper..."), menu_view);
+	auto *show_paper = new QAction(tr("View Inishell &paper..."), menu_view);
 	menu_view->addAction(show_paper);
-	connect(show_paper, &QAction::triggered, this, [=]{ QDesktopServices::openUrl(QUrl(":doc/paper.pdf")); });
-	show_paper->setEnabled(false);
+	connect(show_paper, &QAction::triggered, this, [=]{ QDesktopServices::openUrl(QUrl("https://doi.org/10.5194/gmd-15-365-2022")); });
 }
 
 /**