emacs template for sh files

Make work with template mechanism like b-python.

```sh
#!/bin/bash
#source ~/.bashrc
set -eou pipefail
#cd "$(dirname "${BASH_SOURCE[0]}")"

_main() {
    if (( $# < 1 )); then
        echo 'too few args' 1>2&
        return 1
    fi
}

_main "$@"
```
