[WIP] Enhance attribute docs

[Ininterrompue]

Reformats docstrings.

[BeastyBlacksmith]

That is a good first step in that we now have a clear vision what the output should look like, but in order to not have to update this once we change something in Plots we need to generate these pages from the information in Plots.

For example you can generate a simple mardown document like this:

using Markdown
a = 2
md_doc = MD()
push!(md_doc, md"""
 # Header

`a` has the value $(a).
""")
open("test.md", write = true) do io
     print(io, md_doc)
end

[t-bltg]

Yeah, otherwise this will be a nightmare for maintainability.
These pages have to be auto-generated.

[Ininterrompue]

What would be the cleanest way to make sure there are sections for Subplot and Axis attributes, e.g. annotation, colorbar, etc. so that they show up on the dropdown menu, like how it's done in the commit beforehand? That's an important thing that needs to be done imo. Wouldn't those changes have to be made in Plots.jl since it would be beneficial to be able to do plotattr(:Annotation) in the REPL to print all annotation subplot attributes?

[t-bltg]

I have no idea what the final solution would look like but changes can be made in Plots to accompany this PR. Clarity and concision should be preferred.

[Ininterrompue]

See relevant PR

[t-bltg]

@Ininterrompue, could you post screenshots (after a local docs build against this PR) of what this would look like ?

It's a bit hard to approve without having an overview of the final result ...