Add to the guide how to run mkdocs via a docker image

[jborup]

Suggest to add this section to the README.md

Building this booklet locally but with docker

In some cases you might not want to alter your Python setup and rather go with a docker image instead. This requires docker is running locally on your computer though.

1. docker pull squidfunk/mkdocs-material
2. git clone https://github.com/ibm-cloud-architecture/refarch-eda.git (or your forked repository if you plan to edit)
3. docker run --rm -it -p 8000:8000 -v ${PWD}:/docs squidfunk/mkdocs-material
4. Go to http://127.0.0.1:8000/ in your browser.

Source: mkdcocs with Material in docker

[jbcodeforce]

integrated