[BUGFIX] Add enable_active_wake_mixing field to v3 to v4 documentation and conversion

[misi9170]

As part of the merge of #842 , a new field enable_active_wake_mixing was added to the wake field of the main floris input yaml.

The documentation describing the switch from v3 to v4 missed this detail; additionally, the converter utility convert_floris_input_v3_to_v4.py does not currently add this necessary field, so converted floris input files would currently not actually run.

In this PR, I've fixed the documentation added the enable_active_wake_mixing field to the converter, and tested it by converting a v3 GCH floris input file to v4 and running the first example with it.

I've also fixed the Helix operation model documentation to correctly print the figure and produce turbine powers. I've run a local docs build and the resulting html looks good (see screenshot below), so hopefully that means the deploy-pages build will work.

Note that the power calculation produces warnings because the GCH model (not the EmG model) is being used for the calculation. I think that's fine (maybe even good, for exposition)---this documentation is only supposed to be an exposition of the operation model, which is working as intended. @jfrederik-nrel has updated the power calculation demo to use the EmG model, which avoids raising warnings.

Also included:

• Some broken links to the documentation in the README
• A bugfix @paulf81 pushed to develop to fix the documentation earlier.

[rafmudaf]

@misi9170 since develop and main are at the same commit now, you might consider merging this one to main. That way, you can also fix the broken links in the README here.

[misi9170]

@misi9170 since develop and main are at the same commit now, you might consider merging this one to main. That way, you can also fix the broken links in the README here.

That's a good idea. I'll add those fixes later today. Will we need a new release tag, or is it fine to merge directly to main (and then back to develop) without a release tag in that case?

[rafmudaf]

I'd bet that there will be more things to fix in the next couple of weeks, so I would wait to aggregate them into v4.0.1.

[jfrederik-nrel]

Looks good, Misha!

[paulf81]

This looks good, thank you @misi9170