Improve documentation and implementation of W&B options

[utensil]

1. These options are essentially mapping to the W&B environment variables, for their usage, users need to search and check https://docs.wandb.ai/guides/track/environment-variables#optional-environment-variables , https://docs.wandb.ai/ref/python/watch etc. It might be good to add this link to the readme, and suggest a common usage
2. The implementation could be optimized to just automatically map anything that starts with wandb_ to the same env var

discord discussion: https://discord.com/channels/1104757954588196865/1111279858136383509/1121703569029091412

[NanoCode012]

We need to make sure to migrate any old/incorrect configs and check for old env within validate_config..

[NanoCode012]

Improved by #361

[NanoCode012]

Sorry, I accidentally closed

[tcapelle]

Hello, W&B Eng here, I can help with this. Also we should probably not explicitly set the id as it's better if it is autogenerated. We could potentially give the user the option to setup the run_name, this is what gets displayed on the UI.
Basically, we replace this with the WANBD_NAME env variable.

We could probably have something like this:

def setup_wandb_env_vars(cfg):
    for key in cfg.__dict__:
        if key.startswith('wandb_'):
            value = cfg.get(key, "")
            if value and len(value) > 0:
                os.environ[key.upper()] = value
            elif key == 'wandb_mode' and value == "offline":
                os.environ["WANDB_MODE"] = value
            else:
                os.environ["WANDB_DISABLED"] = "true"

    # Enable wandb if project name is present
    if cfg.get('wandb_project', "") and len(cfg.get('wandb_project', "")) > 0:
        cfg.use_wandb = True