Merge pull request #1864 from frivoal/widows-orphans-clarification

[css-break-3] Clarify the definition of widows and orphans

Author: frivoal

css-break-3/Overview.bs

@@ -412,10 +412,14 @@ Breaks Between Lines: 'orphans', 'widows'</h3>
   Name: orphans, widows
   Value: <<integer>>
   Initial: 2
-  Applies to: block containers
+  Applies to: <a>block containers</a> that establish new <a>inline formatting contexts</a>
   Inherited: yes
   </pre>
 
+  <p>
+    The 'widows' and 'orphans' properties have no effect
+    on <a>block container boxes</a> that contain only <a>block-level</a> boxes.
+  </p>
   <p>
     The 'orphans' property specifies the minimum number
     of line boxes in a block container