Added example to loadXML taken from p5.xml.js

[bomoko]

Hi all,

This is a partial (and I hope, temporary) fix for issue #1954. Specifically, it adds an example for loadXML.
This example is taken directly from io/p5.xml.js.

I've been working on this for a few days, and wanted to get something submitted.

I've actually written a number of examples of loadXML calls (both invoked inside preload and with a callback), but I've had real trouble getting them to work locally inside the p5.js-website framework.
It's possible I'm building the documentation incorrectly, but every other example that doesn't use loadXML seems to run just fine (I'm getting this weird error where the parseXML function isn't being found, but the examples run just fine if I run them outside of the docs).

It's my suspicion that this is why the only loadXML example we do have is invoked with the "norender" class, and why the documentation for loadXML itself mentions the existence of an example, even though there is no example to be had.

So I hope this will do for the moment, I'm going to try dig into the parseXML issue a little more, and if I can't work out what's going on I'll open a separate issue for that.

Thanks :)

[lmccart]

thanks! I suspect the local documentation building hasn't been updated since we changed the website structure. when I test, I typically just build the reference, manually drop it into my website repo and build that and look at it all. not exactly simple and convenient :
that's my recollection but I haven't looked closely recently so please feel free to open an issue with more specifics of what you notice.