add R sample function and readme

Signed-off-by: Chanyub Park <mrchypark@gmail.com>

sample-functions/BaseFunctions/R/README.md

@@ -0,0 +1,34 @@
+BaseFunction for R
+================
+
+Use this FaaS function using R.
+
+**Deploy the base R function**
+
+(Make sure you have already deployed FaaS with ./deploy\_stack.sh in the root of this Github repository.
+
+-   Option 1 - click *Create a new function* on the FaaS UI
+
+-   Option 2 - use the [faas-cli](https://github.com/alexellis/faas-cli/) (experimental)
+
+<!-- -->
+
+    # curl -sSL https://get.openfaas.com | sudo sh
+
+    # faas-cli -action=deploy -image=functions/base:R-3.4.1-alpine -name=baser
+    200 OK
+    URL: http://localhost:8080/function/baser
+
+**Say Hi with input**
+
+`curl` is good to test function.
+
+    $ curl http://localhost:8080/function/baser -d "test"
+
+**Customize the transformation**
+
+If you want to customise the transformation then edit the Dockerfile or the fprocess variable and create a new function.
+
+**Remove the function**
+
+You can remove the function with `docker service rm baser`.