Conventions on documenting a function

[chrisvoncsefalvay]

(I've made a good faith effort to find anything relevant on this but didn't - I apologise if I overlooked something, please feel free to point me to the original post if I'm about to reinvent the wheel here)

I was wondering if there were a convention on the content and structure of the docstring for functions. Consider, for instance, PEP257 in Python. Is there something equivalent for Julia? I've been a little surprised by how little documentation some functions have (when compared to e.g. Python - I appreciate this is an unfair comparison) and thought I'd help out by seeing if I could start documenting a few, but I don't want to do so without knowing the right way to declare arguments and their types, etc.

Thanks!

[elextr]

IIUC its just starting to be defined, see #9447

[mbauman]

This is a dup of #8966.