adding a Dockerfile to run a simple C HelloWorld

Dockerfile

+# use alpine as base image
+FROM alpine as build-env
+# install build-base meta package inside build-env container
+RUN apk add --no-cache build-base
+# change directory to /app
+WORKDIR /app
+# copy all files from current directory inside the build-env container
+COPY . .
+# Compile the source code and generate hello binary executable file
+RUN gcc -o hello helloDocker.c
+# run the program
+ENTRYPOINT ["/app/hello"]