Add description on custom_powerplants use

[carlosfv92]

*Added some additional lines in the commented section of the build_powerplants.py file, with some comments on how to allow the proper configuration/formating of a custom_powerplants.csv file that can be used in the buil_powerplants rule

Closes # (if applicable).

Changes proposed in this Pull Request

Checklist

• [x ] I consent to the release of this PR's code under the GPLv3 license and non-code contributions under CC0-1.0 and CC-BY-4.0.
• [x ] I tested my contribution locally and it seems to work fine.
• Code and workflow changes are sufficiently documented.
• Newly introduced dependencies are added to envs/environment.yaml and envs/environment.docs.yaml.
• Changes in configuration options are added in all of config.default.yaml and config.tutorial.yaml.
• Add a test config or line additions to test/ (note tests are changing the config.tutorial.yaml)
• Changes in configuration options are also documented in doc/configtables/*.csv and line references are adjusted in doc/configuration.rst and doc/tutorial.rst.
• A note for the release notes doc/release_notes.rst is amended in the format of previous release notes, including reference to the requested PR.

[pz-max]

Hi @carlosfv92 ,
Thanks for the contribution. The documentation string is automatically used to compile the documentation. Your current contribtuion looks like this:

I would recommend compiling the documentation locally. We have some documentation how to do this here. I observed some issue with the docs and will raise in a moment a PR on your fork 👍

[pz-max]

@carlosfv92 , please review and accept this PR carlosfv92#2 (will be automatically added here when you accept)

[pz-max]

looks good now. Thanks for the contribution @carlosfv92 :)

[carlosfv92]

Happy to help!