Document <webview>.setZoomFactor/Level as public

docs/api/web-view-tag.md

@@ -492,6 +492,21 @@ Sends an input `event` to the page.
 See [webContents.sendInputEvent](web-contents.md#webcontentssendinputeventevent)
 for detailed description of `event` object.
 
+### `<webview>.setZoomFactor(factor)`
+
+* `factor` Number - Zoom factor.
+
+Changes the zoom factor to the specified factor. Zoom factor is
+zoom percent divided by 100, so 300% = 3.0.
+
+### `<webview>.setZoomLevel(level)`
+
+* `level` Number - Zoom level
+
+Changes the zoom level to the specified level. The original size is 0 and each
+increment above or below represents zooming 20% larger or smaller to default
+limits of 300% and 50% of original size, respectively.
+
 ### `<webview>.showDefinitionForSelection()` _macOS_
 
 Shows pop-up dictionary that searches the selected word on the page.