Update README with docker instructions

README.md

@@ -63,11 +63,14 @@ If so, find us at the [support desk](https://support.opensciencegrid.org).
 ### Using Local Computer for Developement
 
 To make changes to the website clone the files and run the below line to run the container. 
+
+```shell
+docker run -it -p 8002:8000 -v $PWD:/app -w /app ruby:2.7 /bin/bash
 ```
-docker run -it -p 8002:8000 -v $PWD:/app -w /app ruby:2.6.8 /bin/bash
-```
+
 In the container run the below line to build the website. 
-```
+
+```shell
 gem install bundler:2.2.30
 bundle install
 bundle exec jekyll serve --watch --config _config.yml -H 0.0.0.0 -P 8000