added descriptions of the EIA861 data

[Nancy9ice]

Overview
Closes this Google Season of Docs Task:
Update the information of data sources that have missing information under their headings.
Note:
Only the EIA861 data had missing information in its headings so this was updated.

What problem does this address?
This helps users to know more information about the data sources ingested into the PUDL database

Testing
How did you make sure this worked? How can a reviewer verify this?

I ran the command make docs-build and checked if my changes reflected correctly locally

@aesharpe @zaneselvans

[aesharpe]

Lots of ideas! Thanks for filling in these blank sections!

I have some thoughts on the "Background" section as well. I think it would be nice to add something similar to the current 860 docs with the Schedules fleshed out:

As of 2024, the EIA-861 Form is organized into the following schedules:

You can find the schedules in the most recent form instructions (https://www.eia.gov/survey/form/eia_861/instructions.pdf)

Another thought that is out of scope but I want to mention is the harvesting process. We don't really mention this in our documentation, but we should! It's an integral part of how we process EIA860 and 923 data (notably, not 861). And feels like something that should come up on the Data Source pages or somewhere else.

[Nancy9ice]

Lots of ideas! Thanks for filling in these blank sections!

I have some thoughts on the "Background" section as well. I think it would be nice to add something similar to the current 860 docs with the Schedules fleshed out:

As of 2024, the EIA-861 Form is organized into the following schedules:

You can find the schedules in the most recent form instructions (https://www.eia.gov/survey/form/eia_861/instructions.pdf)

Another thought that is out of scope but I want to mention is the harvesting process. We don't really mention this in our documentation, but we should! It's an integral part of how we process EIA860 and 923 data (notably, not 861). And feels like something that should come up on the Data Source pages or somewhere else.

Please could you enlighten me on how this harvesting process works so I'll know what to add to the docs

[aesharpe]

Please could you enlighten me on how this harvesting process works so I'll know what to add to the docs

Yes! I will make a new issue about this with some detail. We don't have a address this as part of this PR.