Update navigatorios.md (facebook#438)

dalebaldwin · charpeni · commit 17b54722842d · 2018-06-29T17:00:27.000-04:00
Clarifying how the translucent prop changes where screens are rendered in relation to the status bar.
diff --git a/docs/navigatorios.md b/docs/navigatorios.md
@@ -282,7 +282,7 @@ The default text color of the navigation bar title.
 
 ### `translucent`
 
-Boolean value that indicates whether the navigation bar is translucent by default
+Boolean value that indicates whether the navigation bar is translucent by default. When true any screens loaded within the navigator will sit below the status bar and underneath the navigation bar. To have screens render below the navigation bar set to false.
 
 | Type | Required |
 | ---- | -------- |
