add R sample function and readme

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

sample-functions/BaseFunctions/R/README.Rmd

@@ -0,0 +1,42 @@
+---
+title: "BaseFunction for R"
+output: github_document
+---
+
+```{r setup, include=FALSE}
+knitr::opts_chunk$set(echo = TRUE)
+```
+
+Use this FaaS function using R.
+
+**Deploy the base R function**
+
+(Make sure you have already deployed FaaS with ./deploy_stack.sh in the root of this Github repository.
+
+* Option 1 - click *Create a new function* on the FaaS UI
+
+* Option 2 - use the [faas-cli](https://github.com/alexellis/faas-cli/) (experimental)
+
+```
+# curl -sSL https://get.openfaas.com | sudo sh
+
+# faas-cli -action=deploy -image=functions/base:R-3.4.1-alpine -name=baser
+200 OK
+URL: http://localhost:8080/function/baser
+```
+
+**Say Hi with input**
+
+`curl` is good to test function.
+
+```
+$ 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`.