Update README.md

lomik · web-flow · commit 2674607cf6e7 · 2018-10-12T00:02:59.000+03:00
diff --git a/README.md b/README.md
@@ -62,6 +62,7 @@ majorGridLineColor = "white"
 minorGridLineColor = "grey"
 areaAlpha = "NaN"
 fontName = "Sans"
+bgcolor = "black"
 ```
 
 ## URI Parameters
