My specific question is how is the parameter from a slash command passed to be used in the URL? That question is not addressed in the documentation.
Everyone repeats the same examples across various websites and no one is actually addressing how the parameter is passed.
It not good showing a section of a a POST when the slash command itself has no faculity to specify a post, that is called a webhook.
Please respond to this query if you have actually created a slash command with parameters.