Minor: fix sentence (#29160)

"Popovers whose both title..."

site/docs/4.3/components/popovers.md

@@ -304,7 +304,7 @@ Initializes popovers for an element collection.
 
 #### `.popover('show')`
 
-Reveals an element's popover. **Returns to the caller before the popover has actually been shown** (i.e. before the `shown.bs.popover` event occurs). This is considered a "manual" triggering of the popover. Popovers whose both title and content are zero-length are never displayed.
+Reveals an element's popover. **Returns to the caller before the popover has actually been shown** (i.e. before the `shown.bs.popover` event occurs). This is considered a "manual" triggering of the popover. Popovers whose title and content are both zero-length are never displayed.
 
 {% highlight js %}$('#element').popover('show'){% endhighlight %}