Add docker container be added to the docs

[navaneeth-dev]

https://infisical.com/docs/cli/overview

Does not show docker, for people using flatcar/coreos containers are recommended.

I am able to run the docker container, but there is no info about it online. Had to look at the GH actions to find out.

docker run infisical/cli -h                                                                                                                                                         
Unable to find image 'infisical/cli:latest' locally                                                                                                                                   
latest: Pulling from infisical/cli                                                                                                                                                    
9824c27679d3: Already exists                                                                                                                                                          
935653b94df1: Pull complete 
548258e29a08: Pull complete 
f146182e8354: Pull complete 
Digest: sha256:fe149a8588783cb01498d8a899c7fcbf92e6bc0db214416cce8b90f52a285278
Status: Downloaded newer image for infisical/cli:latest
Infisical is a simple, end-to-end encrypted service that enables teams to sync and manage their environment variables across their development life cycle.

Usage:
  infisical [command]

Available Commands:
  agent           Used to launch a client daemon that streamlines authentication and secret retrieval processes in various environments