Documentation updates

[amaloney]

Introduction

Broken links

• getting started
• user guide
• api
• move gitter page to discourse and discord

Getting started

• Remove Python 3.9 as supported
• Add Python 3.13 as supported

Introduction

• link to datashader via the words (open-source) is to bokeh/datashader but it resovles to holoviz/datashader
• link to holoviews and bokeh use http, but they should use https
• link to the 3-interactivity resolves to the getting started introduction
• link to the user guide resolves to the same getting started intro page
• path for reading data in NYC taxi trips is ambiguous
• user guide link at the bottom is also broken

Pipeline

• pipeline image is broken, should be ../assets/images/pipeline2.png
• from a UI perspective, make the holoviews image the same size as the first one, and center the first one
• user guide link in aggregation heading is broken
• extending datashader link in aggregation section is broken
• 2d reductions section one -> once
• casting warning using new xarray in the d3+d5... images

Colormapping with negative values

• diverging colormap link broken
• fix future warning with pandas

Interactivity

• fix all the http links to use https
• fix broken link image ..assets/...
• fix bokeh docs links
• similar assets issue

HoloView+Bokeh

• broken link to plotting pipeline
• broken link in rich display
• fix scroll of images UX

[amaloney]

@hoxbro there are a large number of things needing updated in the docs, that I'll work on for v0.17.0