We have RSD discovery for the api, so in the source it is:

<link rel="EditURI" type="application/rsd+xml" href="http://192.168.0.190/w/api.php?action=rsd" />

Which then has the content:

<?xml version="1.0"?><rsd version="1.0" xmlns="http://archipelago.phrasewise.com/rsd"><service><apis><api name="MediaWiki" preferred="true" apiLink="http://192.168.0.190/w/api.php" blogID=""><settings><docs xml:space="preserve">https://www.mediawiki.org/wiki/API</docs><setting name="OAuth" xml:space="preserve">false</setting></settings></api></apis><engineName xml:space="preserve">MediaWiki</engineName><engineLink xml:space="preserve">https://www.mediawiki.org/</engineLink><homePageLink xml:space="preserve">http://192.168.0.190/wiki/Main_Page</homePageLink></service></rsd>

I guess this is enough.
I must have been unlucky with the wikis I looked into (they didn't have it): when was it added? I'll add the info to the docs.

(In reply to comment #2)

I guess this is enough.
I must have been unlucky with the wikis I looked into (they didn't have it):
when was it added? I'll add the info to the docs.

r75621

So should be in 1.17 onwards

I could see reason to put this somewhere more user visible too

(In reply to comment #3)

I could see reason to put this somewhere more user visible too

Agreed. I'll write a patch adding a link to Special:Version

https://gerrit.wikimedia.org/r/4797

I don't think those paths are appropiate to be listed in Special:Version

They are just configuration settings. It's fine to expose them in the API, but not in Special:Version, at least not by default.