Most issues regarding search are raised at Documenter.jl. And, if you search this Discourse you’ll see that the documentation search issues have been encountered before. I don’t know what the technical problems are (overly-fuzzy searching was one issue, if I remember correctly), and it’s often the case that you don’t get any matches or get far too many. But search is a difficult problem…
I understand that the solution will eventually be the search tool at pkg.julialang.org, which is currently under construction, but working quite well for some (but not all) packages already. (A search for “generators” gives many hits, but at first glance I couldn’t see the obvious result for the Julia manual… ¯\_(ツ)_/¯ )