add Joanna rocks parameters (#286)

params/joanna_rocks.R

@@ -0,0 +1,16 @@
+# !! PLEASE DO NOT EDIT THIS FILE !!
+# ** make a copy and edit that instead **
+# ________________________________________________
+# input parameters
+
+# sigma2: 0 < value < 5
+sig2 <- 2
+
+# e.g. "anas_krystallinus"
+species.name <- "joanna_blahblub"
+
+# e.g. "red"
+color <- "green"
+
+  # tip: pick a color using rstudio colour picker.
+  # Addins > Colour Picker (to install: install.packages("colourpicker"))