properly added featherlight and detect swipe as submodules

.gitmodules

@@ -0,0 +1,6 @@
+[submodule "rsc/js/detect_swipe"]
+	path = rsc/js/detect_swipe
+	url = https://github.com/marcandre/detect_swipe.git
+[submodule "rsc/js/featherlight"]
+	path = rsc/js/featherlight
+	url = https://github.com/noelboss/featherlight.git