Add support for "--help" in scripts

[AlexSkrypnyk]

Use this example:

#/ Usage:       ./bake.sh [path/to/manifest.hcl] [path/to/another/manifest.hcl]
#/ Description: Wrapper script for running docker buildx bake with separate manifest files.
#/ Options:
#/   --help: Display this help message
usage() { grep '^#/' "$0" | cut -c4- ; exit 0 ; }
expr "$*" : ".*--help" > /dev/null && usage

Since the scripts are driven by env variables rather than arguments, the usage() from the above may need to be more complex as we would want to see something like:

...
Environment variables:
DREVOPS_SCAFFOLD_EXAMPLE_URL: Example scaffold variable with a default value.
DREVOPS_SCAFFOLD_EXAMPLE_URL_OTHER: Example scaffold variable other with a default value.
...