Build out v4 documentation

[misi9170]

Main pull request for documentation updates for v4. See checklist below for assignments.

Places for adding documentation:

• User Reference: high-level information for normal users, ideally using simple examples
• Theory and Background: Detailed information, including mathematical models.
• Developer Reference: information needed for developers to add to existing capabilities

The major focus of this PR is on getting the User Reference up to speed with changes for v4. However, adding to the Theory and Background and Developer Reference sections is also encouraged :)

When adding documentation to the User Reference, consider:

• What would a normal user need to know to run a simple example and interpret the outputs?
• What basic options does the user have to customize the calculations and performance?
• Could a short example script that produces an output or plot be added to demonstrate the options and functionality? (if so, consider formulating the section as a jupyter notebook)

Assignments

• wind data objects (general, WindRose, TimeSeries, WindTIRose) @paulf81
• Floating wind @bayc
• Value-based optimization @ejsimley , may live on the same file as the wind data objects
• Operation models @misi9170
• Helix @jfrederik-nrel , add to the operation_models_user.ipynb notebook for turbine performance, possibly new notebook for wake model? Unsure.
• Converting from v3 to v4 @rafmudaf @misi9170

Please go ahead and push changes to this branch (v4-ms/docs). To see the compiled docs after you have pushed, see https://misi9170.github.io/floris/index.html (you'll need to wait a few minutes for them to build).

Final steps:

• Final checks @misi9170
• Switch build branch back to develop @misi9170

[paulf81]

I think we should merge this branch soon. One last annoying issue that I wouldn't mind fixing is the first comment block, jupyter-book is collapsing white space (new lines and tab indents) in a way that makes the blocks less readable. There appear to be solutions (one is we can adjust the config.yml file to change this behavior) but maybe someone else could have a quick look?

[misi9170]

One last annoying issue that I wouldn't mind fixing is the first comment block, jupyter-book is collapsing white space (new lines and tab indents) in a way that makes the blocks less readable.

In the interest of moving this forward, I'm going to go ahead and merge. We can open a PR to develop at a later date to address this.