Added markdown example

examples/gadfly_sample.jmd

@@ -0,0 +1,16 @@
+
+# Gadfly
+
+```{julia term=true; fig_width=5}
+using Gadfly
+x = linspace(0, 2π, 200)
+plot(x=x, y = sin(x), Geom.line)
+y = 20
+plot(x=x, y = cos(x), Geom.line)
+```
+
+
+```{julia}
+x = linspace(0, 200)
+println(x)
+```