proposal for rendering images when last value from @example blocks

[tpapp]

This is a feature request. I am wondering if it would be possible to just render plots when they are the last value in @example blocks (& similar).

Currently, the manual suggests something not unlike

```@example
make_my_plot(....)
save_my_plot("filename.svg", ans); nothing # hide
```

![](filename.svg)

What I am proposing is the following:

1. When the block is run, the last value is inspected with Base.Multimedia.showable for a list of predefined MIME types (eg svg, png).

2. If one of them returns true, the corresponding value from show is captured into a file, which is assigned a unique name (eg in a subdirectory dedicated for this purpose, a hash or an integer counter).

3. The image is included in the output.

[fredrikekre]

I thought this is how it works already?

[tpapp]

@fredrikekre: are you sure about this? Can you link a repo where that is used?

[fredrikekre]

https://github.com/fredrikekre/Literate.jl/blob/66e98332c6e63197a7643993acc72faafd7d8d2a/examples/example.jl#L102 which renders as https://fredrikekre.github.io/Literate.jl/v2/generated/example/ for example.

[mortenpi]

We also have the SVG example in the Documenter showcase: https://documenter.juliadocs.org/stable/showcase/#Running-interactive-code

Currently, the manual suggests something not unlike

I think we should update the docs here. I feel that show methods are preferred (although the explicit inclusion can also be useful when the show method can't be used for one reason or another).

[tpapp]

Thanks, I now see that it is working fine, it just needs to be updated in the docs.