Update README.md

Author: bendv

README.md

@@ -5,14 +5,14 @@ Plotting functions for bfast-type objects.
 
 This package can be installed directly from github:
 
-```
+```R
 library(devtools)
 install_github('bendv/bfastPlot')
 library(bfastPlot)
 ```
 
 Try these:
-```
+```R
 ?bfmPredict
 ?bfmPlot
 ```