Update installation instructions for demandlib

[khashashin]

Install instructions are wrong, the named package does not exist.

[p-snft]

Thanks for bringing this up. While installing "demandlib" is still possible, the preferred way now is "pip install oemof.demand". (I assume, this was a typo that went through unnoticed.)

[khashashin]

I see, I first checked the state on pypi and wasn't sure which one is the correct (tbh 3 different name... why? :D)

I'll update the PR

[khashashin]

The update dates are also confusing: version 0.2.2 was updated on 6 April, whereas version 0.2.3a1 was updated back in February.

[p-snft]

There are multiple names because we are renaming demandlib (last updated April 2025, about a year ago) to oemof.demand (updated February 2026, two months ago). However, GitHub does not allow dots in repository names. Thus, we have to use oemof-demand, here. I hope, this makes things clear.

[github-actions]

Coverage report

This PR does not seem to contain any modification to coverable code.

[p-snft]

Thank you for your contribution!

Link check is failing because of a time out. This is a known false positive with the test when run at GitHub. Will merge.