Include changelog as markdown files and show it in the about dialog

public/js/grocy.js

@@ -497,7 +497,8 @@ $("#about-dialog-link").on("click", function()
 {
 	bootbox.alert({
 		message: '<iframe height="400px" class="embed-responsive" src="' + U("/about?embedded") + '"></iframe>',
-		closeButton: false
+		closeButton: false,
+		size: "large"
 	});
 });