Recommend adding #!/bin/bash line about vs-shell-format

[dseynhae]

Why would we recommend this, if it is not necessary, or even not desired:
People are developing scripts that are meant to change the current environment. Which means that those scripts have to be sourced.
A shebang at the start of such script might give the impression that the script is meant to be executed. A well-designed script will not have execution privileges, but still, the shebang is not desired at all for this scenario...

The 'shellcheck' application does it right:

For a script that needs to be sourced, you simply add:

# shellcheck shell=bash

If the script was meant to be executed, then you can indeed add the shebang...

Since shfmt is a formatting tool, and not a general coding style tool, I would leave it to shellcheck to manage this rule...