Add docker support (#11)

* Add Dockerfile and instructions for building and using as a Docker container - thanks, @gourk

Co-authored-by: Simon Willison <swillison@gmail.com>

Author: gourk

Dockerfile

@@ -0,0 +1,5 @@
+FROM python:3.8-alpine
+RUN pip install csv-diff
+WORKDIR /files
+ENTRYPOINT ["csv-diff"]
+CMD ["--help"]

README.md

@@ -112,3 +112,17 @@ You can also import the Python library into your own code like so:
 `diff` will now contain the same data structure as the output in the `--json` example above.
 
 If the columns in the CSV have changed, those added or removed columns will be ignored when calculating changes made to specific rows.
+
+## As a Docker container
+
+### Build the image
+
+    $ docker build -t csvdiff .
+
+### Run the container
+
+    $ docker run --rm -v $(pwd):/files csvdiff
+
+Suppose current directory contains two csv files : one.csv two.csv
+
+    $ docker run --rm -v $(pwd):/files csvdiff one.csv two.csv