docs: added stargazer plot to stats page

Author: ErikBjare

stats.pug

@@ -8,7 +8,16 @@ article.container
   header
     h1 Statistics
 
+
+  h2 Downloads
+
   p
     | Here you can see some download statistics, updated every 24h.
 
   img(src="/img/stats/downloads.png")
+
+
+  h2 Stargazers over time
+
+  a(href="https://starchart.cc/ActivityWatch/activitywatch")
+    img(title="Stargazers over time" src="https://starchart.cc/ActivityWatch/activitywatch.svg")