[css-page-floats] Remove parts about column spanning concerned under 'over-constrained layouts'

Author: johanneswilm

css-page-floats/Overview.bs

@@ -1049,11 +1049,7 @@ p { float-reference: page; float: top; float-defer: last }
   goals are:
 
   <ol>
-    <li>
-      honor basic multi-column layout ('columns', 'column-span: all',
-      'column-gap' etc)
-    <li>honor 'column-span: &lt;integer>'
-    <li>honor 'clear: top/bottom/pcolumn/page'
+    <li>honor 'clear: top/bottom'
     <li>honor 'float-defer'
     <li>honor 'float: top/bottom'
     <li>display all content (as described by other CSS properties)