That menu option isn't supposed to appear in the New Item menu, but it was included by mistake in some recent versions.
You should almost never be creating webpage items manually. You want to save webpages, and as much else as possible, using the Zotero Connector in your browser. See this section (and the rest of the page) for more information:
@elrica: I was bothered by this too. Note that if you manually create a new item of any type, you can then change the Item Type to "Web Page". Hope that helps!
@dstillman: I needed to manually create some web page items earlier today because the Zotero Connector in Chrome can't do it for some reason. I do plan to follow up as describe in https://www.zotero.org/support/getting_help but I don't have time right now. So, it'd be nice if Zotero helped me do this as much as possible. If you don't feel that Web Page should be an obvious choice on the New Item menu, maybe put make these available as a 2nd tier under an "Advanced..." entry?
because the Zotero Connector in Chrome can't do it for some reason
You should start a new thread and say more. There's almost no reason you should ever need to create a webpage item for a live website manually. If you can't save from your browser, there's some sort of fundamental breakage with your installation and you should fix that before continuing to use Zotero.
Upgrade Storage
You should almost never be creating webpage items manually. You want to save webpages, and as much else as possible, using the Zotero Connector in your browser. See this section (and the rest of the page) for more information:
https://www.zotero.org/support/adding_items_to_zotero#manually_adding_items
@dstillman: I needed to manually create some web page items earlier today because the Zotero Connector in Chrome can't do it for some reason. I do plan to follow up as describe in https://www.zotero.org/support/getting_help but I don't have time right now. So, it'd be nice if Zotero helped me do this as much as possible. If you don't feel that Web Page should be an obvious choice on the New Item menu, maybe put make these available as a 2nd tier under an "Advanced..." entry?