Update and clarify FERC 2021 data description on Datasette

[katie-lamb]

Describe the bug

When accessing FERC data on Datasette I currently find the descriptions and different FERC data links to be confusing. For example the ferc1 link says:

This database is a concatenation of all the individual annual FERC Form 1 Visual FoxPro databases published from 1994-2021

Is this data actually inclusive of 2021? Shouldn't all the 2021 be in the XBRL data links? Should this ferc1 data be renamed ferc1_1994_2020 or ferc1_dbf something? I also think the XBRL data (ferc1_xbrl) could potentially have a more clear description that says how FERC transitioned in 2021 and that the XBRL data is only 2021.

Bug Severity

How badly is this bug affecting you?

• Low: The bug isn't causing me problems, but something's still wrong here.

To Reproduce

Expected behavior

I really only ran into this confusion when trying to send an email explaining how to access the 2021 data.

### In-scope
- [ ] Update description of DBF-based form-1 datasette description
- [ ] Update description of XBRL-based form-1 datasette description

Out-of Scope

• [ ] Change name of [ferc1](https://data.catalyst.coop/ferc1) to ferc1_dbf to reflect naming convention of {agency}{form number}_{format}
• [ ] case down and all the uses of ferc1.sqlite in pudl