Make hc_add_onclick_korap_search work with scatter plots

Change-Id: I176c37ee94fcf3da989ee0cb761e331efc2dc8e0
diff --git a/R/hc_add_onclick_korap_search.R b/R/hc_add_onclick_korap_search.R
index 6d1508e..710c1cb 100644
--- a/R/hc_add_onclick_korap_search.R
+++ b/R/hc_add_onclick_korap_search.R
@@ -39,5 +39,6 @@
     spline = onclick_hc_options,
     column = onclick_hc_options,
     bar = onclick_hc_options,
+    scatter = onclick_hc_options,
     pie = onclick_hc_options)
 }