http://dochub.mongodb.org/core/serversidecodeexecution

This link is present in the server help message for the eval command:

> db.runCommand({'eval':null, help:true})
{
	"help" : "help for: eval Evaluate javascript at the server.\nhttp://dochub.mongodb.org/core/serversidecodeexecution",
	"lockType" : 0,
	"ok" : 1
}

Which lives here:
https://github.com/mongodb/mongo/blame/master/src/mongo/db/dbeval.cpp#L135-L137

This URL originated with DOCS-217. Given that the old docs wiki is offline, it's probably worth checking of other dochub url added there are bad.