Document `docker` source installation

We need better documentation on how to setup the docker source. This was a conversation in our chat:

Hi there,
I'm once more considering Vector to replace my current "log ingestion process".
All the app that we want to monitor run on a docker container. So currently, we use fluentbit as the "log driver" to parse / transform the logs.
I've looked at vector's docker source module and it seems to work quite differently than fluentbit.
In our case fluentbit itself run in a container, from what I understood, the plugin was installed directly inside of docker, docker then route the logs to a port... inside a container.
If I wanted to use vector I would have to install on the server itself, bare metal ?
Would it be possible to run a container with both vector and docker installed in it so that I don't require to install docker to the server ? I'm far from a docker expert, but that seems like it could potentially cause some sort of problems (to run a docker inside a container) ?
Maybe you have some experience with a similar flow ?
Cheers.

And @a-rodin responded with:

Hi, it is possible to pass the Docker socket from the host inside the Vector container to allow Vector communicate with the Docker engine. It can be done by mounting /var/run/docker.sock. For example if you run Vector as docker run vector, an additional option -v/var/run/docker.sock:/var/run/docker.sock can be added to the list of command line arguments to do this. For docker-compose.yml it is possible to mount it like this:

version: '3'                                                                                                            

services:                                                                                                               
  vector:                                                                                                               
    image: timberio/vector:nightly-alpine                                                                               
    volumes:                                                                                                            
      - ./vector.toml:/etc/vector/vector.toml                                                                           
      - /var/run/docker.sock:/var/run/docker.sock

Note that if you use console sink, you might want to not include the Vector's container to the list of containers it watches for.

Start by locating the Docker source documentation and reviewing the source module's setup requirements. Document running Vector in a container with /var/run/docker.sock mounted, including the docker run and docker-compose.yml examples from the issue. Mention excluding Vector's own container when using the console sink; done means users can follow the documented container setup.