replaced "an" with "a" (#37707)

data/reusables/projects/select-a-cell.md

@@ -1,4 +1,4 @@
 - Hold <kbd>Command</kbd> (Mac) or <kbd>Ctrl</kbd> (Windows/Linux) and select each cell.
-- Select an cell then press <kbd>Shift</kbd>+<kbd>↑</kbd> or <kbd>Shift</kbd>+<kbd>↓</kbd> to select additional cell above or below the selected item.
-- Select an cell then press <kbd>Shift</kbd> and select another item to select all items between the two items.
+- Select a cell then press <kbd>Shift</kbd>+<kbd>↑</kbd> or <kbd>Shift</kbd>+<kbd>↓</kbd> to select additional cell above or below the selected item.
+- Select a cell then press <kbd>Shift</kbd> and select another item to select all items between the two items.
 - Holding your mouse button down, move the cursor over the cells you want to select.