Improve go-ftw / Docker documentation

[theseion]

Findings by @dune73:

• I had to install docker-compose (Ubuntu 22.04). Docker compose command becomes docker-compose. The documentation explains the need for docker-compose in older installs, but it only explains this under go-ftw, not in the docker section, where I kind of expect such an explanation.
• The code block uses > as prompt, while other code blocks use $.
• The code block does not explain you need to be root to run this. sudo would probably make this easier. The twist is that you may not be root to install go-ftw afterwards or the binary can't be found for the testing user.
• The docker ps is a bit hidden within the same code block as the compose.
• I'm getting a go-httpbin container instead of the httpbin indicated in the docker ps output
• The ftw files presented further down below in the documentation do not correspond with the docker container composed. That means you need to adjust the log file within the .ftw.yaml. The doc explains that we're mounting the log volumes, but it does not indicate the path and I had to look for it in the compose file without this being explained anywhere. We are providing docker-compose.yaml. Why don't we provide a preconfigured .ftw.apache.docker.yaml etc.?