Developer Guide is missing

[MarcSkovMadsen]

Request

Add a developer guide.

Motivation

There is no developer guide making it very hard for potential contributors.

I for one would like to try out contributing to HoloViews.

[MarcSkovMadsen]

Workaround

For now inspiration can be found in the hvPlot developer guide. That guide does not work for my though. Thus I created a PR here to fix it holoviz/hvplot#887. If you can review and approve it, please do. It wont take long.

A readable version is here https://github.com/holoviz/hvplot/blob/33d1fa9f1a6570de13843102d662464acb73c2b8/doc/developer_guide/index.rst

You can use it if you replace hvplot by holoviews.

[MarcSkovMadsen]

I can see that flake8 does not get installed when I follow the above. I see

$ doit test_flakes
.  test_flakes
/bin/sh: 1: flake8: not found
TaskError - taskid:test_flakes
Command error: 'flake8 "holoviews"' returned 127