Fix pronoun syntax for aguestuser

@aguestuser added himself in !191 (merged) and used the syntax pronoun: he/they but that doesn't seem right. It produces a link to https://pronoun.is/he/they, which pronoun.is interprets as specifying different parts of speech. It doesn't seem likely that that's what was intended.

I grepped through the repo and found another user, @sanketh, had specified pronoun: he?or=they, which comes out as https://pronoun.is/he?or=they, and is rendered in what seems to be an appropriate way by pronoun.is. So, thanks for that example, sanketh.

@aguestuser: I hope I have understood your intent correctly and that you will appreciate this change :-).