[bug#72925] [PATCH v3] adding jpm package

[jgart]

(un)related to this,

what do people think of having language specific guides for using `guix shell` with particular programming languages?

not unlike this Nix guide that shows how to use Python in a `nix shell` to develop on a flask application:

https://nix.dev/guides/recipes/python-environment.html

would be cool to document the expected workflow for a Guix user using jpm and guix to develop on janet software, for example.

we can continue my thought on #guix-devel didn't mean to distract ;()

wdyt,

jgart

https://whereis.xn--q9jyb4c/