document query string options

[pkra]

From mathjax/MathJax-dev#20 (comment)

There are already several other parameters that I don't think are documented anywhere. The config parameter is certainly documented, but there is also locale=... (e.g., locale=fr), delayStartupUntil=... (which can be set to none, onload or configured), noDOMContentEvent (which is obsolete now, but was a way around using the DOMContentLoaded event to start MathJax's processing phase, when that was less well supported), and NoMathPlayer (which prevented MathJax from trying to use MathPlayer even if it was available). And now noContrib.