docs: add missing lane property and fix measureElement method reference in VirtualItem interface and docs

Author: wo-o29

docs/api/virtual-item.md

@@ -11,6 +11,7 @@ export interface VirtualItem {
   start: number
   end: number
   size: number
+  lane: number
 }
 ```
 
@@ -54,7 +55,7 @@ The ending pixel offset for the item. This value is not necessary for most layou
 size: number
 ```
 
-The size of the item. This is usually mapped to a css property like `width/height`. Before an item is measured with the `VirtualItem.measureElement` method, this will be the estimated size returned from your `estimateSize` virtualizer option. After an item is measured (if you choose to measure it at all), this value will be the number returned by your `measureElement` virtualizer option (which by default is configured to measure elements with `getBoundingClientRect()`).
+The size of the item. This is usually mapped to a css property like `width/height`. Before an item is measured with the `Virtualizer.measureElement` method, this will be the estimated size returned from your `estimateSize` virtualizer option. After an item is measured (if you choose to measure it at all), this value will be the number returned by your `measureElement` virtualizer option (which by default is configured to measure elements with `getBoundingClientRect()`).
 
 ### `lane`