From what I understand you get a full node and a witness node. If it is dockerized then it probably just means that you need to setup the directories for the docker volumes and spin it up with $ docker-compose up
Which documentation are you referring to?

See this comment by themarkymark who is a witness:
https://steemit.com/programming/@netscape101/re-themarkymark-re-toresto-re-themarkymark-python-tips-secrets-module-new-in-3-6-20180410t135130860z#@themarkymark/re-netscape101-re-themarkymark-re-toresto-re-themarkymark-python-tips-secrets-module-new-in-3-6-20180410t161229283z

"Witness node is what produces blocks and is used to secure the blockchain.
A full node is what is used to handle calls to the blockchain. It hosts the API to allow applications to query the blockchain and to make changes.
Then you have a seed node which is read only to help speed up the network."