Initial clean-up and reorganization of PowerFlows documentation

[kennedy-mindermann]

The existing PowerFlows documentation needs to be cleaned up prior to reorganizing with the new Diataxis format. This includes:

• Upgrading to Documenter > 1.0 and resolving errors to enforce strict compilation
• Adding .md formatting to the formatter script
• Proof-reading for formatting and misformatted code references
• Adding hyperlinks everywhere

[rodrigomha]

I will add here that we need to properly do the Docs. We don't really have documented all the capabilities in our existing docs.

[GabrielKS]

I will add here that we need to properly do the Docs. We don't really have documented all the capabilities in our existing docs.

And probably even before that we need to properly solidify the interface, see #38.