[Feature] Setup some documentation!

[willGraham01]

Is your feature request related to a problem? Please describe.

We should document how the widget works, as we are writing it.

Describe the solution you'd like

• README with overall ethos, structure, important classes, and ideas for organisation.
• Docstrings for all public-facing methods and non-intuitive private methods.
• Tests, where not obviously named, should also have docstrings.

Describe alternatives you've considered

Additional context

[K-Meech]

We should make sure all docstrings use numpydoc style - this is what both Napari and Brainglobe use. (currently there are some reST style docstrings)

[willGraham01]

README needs an infodump. We should probably have the following sections:

• Overview
  • What this plugin does?
  • Ethos (it's an entirely separate way to interact with layers, do not use the other viewer except for adding layers)
  • Outlook - hopefully this plugin widget will just replace the existing layerlist viewer instance
• Implementation details
  • Key classes (GroupLayerNode, GroupLayer, and the QT things)
  • Our use and subclassing of Group and Node
  • Explain the decision to not make Layers into a Node subclass, but instead to track pointers to them
  • Indexing and fun times
  • Event propagation (down the tree)
  • The debugger entry is still there
• Todo
  • Desirable features
  • Known bugs and issues (non-breaking but poor UX)
  • Known bugs and issues (breaking)

[K-Meech]

I'll start writing the Overview + Todo sections for the README

[willGraham01]

I'll start tackling the Implementation section now

[willGraham01]

We now have each of the requested items in the issue list present in the repository. Going to close this issue now, but in future we might want to look into a docs build if the plugin gets a lot bigger than it currently is.