delete the .page-header and its docs

Author: mdo

docs/components/page-header.md

@@ -91,16 +91,6 @@ mark,
 }
 
 
-// Page header
-// -------------------------
-
-// .page-header {
-//   padding-bottom: (($line-height-computed / 2) - 1);
-//   margin: ($line-height-computed * 2) 0 @line-height-computed;
-//   border-bottom: 1px solid @page-header-border-color;
-// }
-
-
 // Lists
 // -------------------------