Data_adapter Readme-update

[HeddaGardian]

I think the address for the clone has changed from: `git clone https://github.com/rl-institut/data_adapter.git to
https://github.com/sedos-project/data_adapter.git.

Also the step:
install data_adapter_oemof package using poetry, via: poetry install
could be more specific: conda install poetry.

For users to really being able to use the tool, it could be helpful to write some steps for how the data download could be achieved.

[SabineHaas]

I think the address for the clone has changed from: `git clone https://github.com/rl-institut/data_adapter.git to
https://github.com/sedos-project/data_adapter.git.

thanks for reporting! I've adapted this in dev branch