Add support for script comment/description

I have been playing around with wire it and I love it!

I have always wished for `package.json` comments, but we don't have them even in 2024!

Many times we have commands that are too complex, and an explanation would be of great help.

What about adding a `comment` or `description` prop to the wireit scripts?

I know we can add any prop to the script object that is unrelated to wireit and wireit won't mind those, but my suggestion is primarily to have best practices in place and allow auto completions via VS Code extension.

Something like this

```json
"wireit": {
"cleanup": {
"comment": "Delete the paths that are not version controlled.",
"command": "rm -rf some/path/* && rm -rf some/other/path/* && rm -rf some/other/related/path/*"
},
}
```