Accessibility alt text for any images

[Lextuga007]

A consideration for any logos or images that are generated for accessibility would be really good. Reference: https://twitter.com/FrankElavsky/status/1414707183867109377

Ideally all images will have alt text and please consider using some of the RStudio features for generating alt text for plots: https://twitter.com/hadleywickham/status/1394995611427029000

[chrismainey]

We could add some rules, based on the number of points, rebase, the field names, and rules sets to add lab(alt=) to the plots. Bit of work but seems like a good idea for accessibility.

[ThomUK]

Do we have any images in this package @tomjemmett? Would this issue be more applicable to packages downstream of this one?

[tomjemmett]

The images are within vignettes and the readme only - I'm not sure any of these currently have alt text added.

The two ways of doing this are:

1. if the image is directly included via ![](image.png), then you can use `{fig-alt="Alternative text goes here."} quarto docs
2. if the image is rendered via a code chunk you can the fig-alt chunk option (this is for quarto, but should work the same for rmarkdown)

[Lextuga007]

Whilst this work picks up, there are issues related to plotly #206 and #177 and I want to check that the use of plotly is accessible. If not could this be an add-on package rather than in this to be used as a companion?