Add demo that plots plural gender variant frequencies over time

Change-Id: If20630ed7190f5a7744c165e50196efd48c83090
diff --git a/demo/00Index b/demo/00Index
index d2148bb..6000d36 100644
--- a/demo/00Index
+++ b/demo/00Index
@@ -13,3 +13,4 @@
 frequency_by_country_ggplot     Plot frequencies depending on country of publication using ggplot2.
 frequency_by_country_highcharts Plot frequencies depending on country of publication using highcharter.
 collocation_score_by_country    Plot collocation scores depending on country of publication using ggplot2.
+pluralGenderVariants            Plot frequencies of the plular gender variants of a word over time.