Improve usage instructions.

The instructions [imply](https://github.com/jgarzik/brainpro?tab=readme-ov-file#two-paths) that you can either use the CLI locally or go through the docker build instead. However, the docker image just hosts a webpage that redirects you to the websocket.

Further, if you follow the [quick start guide](https://github.com/jgarzik/brainpro?tab=readme-ov-file#two-paths) or the [Userguide](https://github.com/jgarzik/brainpro/blob/main/USERGUIDE.md#installation) and do `cargo build --release` followed by `yo` you will get:
> bash: yo: command not found

Overall, the documentation should be more clear about how to actually use this project, and what the specific requirements are. Also, it should be possible to use the CLI inside a docker container for security reasons, and the docker instructions should include the steps necessary to achieve that.