Combine clone_ferc1 and run_the_etl docs pages.

[zaneselvans]

Overview

• There's a bit of duplication between run_the_etl.rst and clone_ferc1.rst in our development documentation.
• It would be nice to have all of this information in a single place and avoid duplication.
• The two docs pages are separate largely for historical reasons -- pre-Dagster we had entirely different scripts that managed the two processes.
• Now that they've been unified under the same framework, it makes less sense for them to be separate, standalone dev docs pages.

How will we know that we're done?

• No more docs/dev/clone_ferc1.rst
• All of the clone_ferc1.rst content has been integrated into run_the_etl.rst