Add Dockerfile and update README.md

Dockerfile

@@ -0,0 +1,18 @@
+FROM ubuntu:20.04
+
+LABEL version="1.0"
+LABEL description="Docker image for ncdump-json."
+
+ENV DEBIAN_FRONTEND=noninteractive
+
+RUN apt-get update && \
+	apt-get install wget unzip build-essential cmake pkg-config libnetcdf-dev -y && \
+	wget https://github.com/jllodra/ncdump-json/archive/master.zip && \
+	unzip master.zip && \
+	cd ncdump-json-master && \
+	cmake . && \
+	make
+
+WORKDIR /ncdump-json-master
+
+ENTRYPOINT ["./ncdump-json"]

README.md

@@ -21,6 +21,26 @@ It behaves exactly like the original ncdump if you omit the command-line option
 
 ---
 
+**NEW!**: Run it with Docker
+
+* No need to compile anything
+* Run from any Linux machine, OSX, Win10
+
+Steps:
+
+* Install Docker on your computer (https://docs.docker.com/get-docker/)
+* Download this repository (download as zip or clone)
+* CD to repository directory
+* Build the image: `docker build -t ncdump-json .`
+* Test the container: `docker run -it --rm ncdump-json -j tests/socib-buoy.nc`
+* Run the container using your own netcdf file: `docker run -it --rm -v "${PWD}/myfile.nc:/data/myfile.nc" ncdump-json -j /data/myfile.nc`
+
+Note: To build the image, you must be in the same directory as the Dockerfile. 
+To run the container, the -v argument (-v "host path:container path") allows the container to access the .nc file that is on your filesystem. 
+On Win10, it is slightly different because win paths are different from unix paths, google a bit and find more info.
+
+---
+
 Installation:
 
 * Download latest **release** from https://github.com/jllodra/ncdump-json/releases, **unzip**.