restore page headers, use partial and page frontmatter to organize it

docs/layout/containers.md

@@ -1,6 +1,7 @@
 ---
 layout: page
 title: Containers
+group: layout
 ---
 
 Bootstrap requires a containing element to wrap site contents and house our grid system. Choose from the fixed or fluid width variation.

docs/layout/grid.md

@@ -1,6 +1,7 @@
 ---
 layout: page
 title: Grid system
+group: layout
 ---
 
 Bootstrap includes a powerful mobile-first grid system for building layouts of all shapes and sizes based on a 12 column layout.

docs/layout/media-queries.md

@@ -1,6 +1,7 @@
 ---
 layout: page
 title: Media queries
+group: layout
 ---
 
 Since Bootstrap is designed to be mobile-first, we employ media queries in our CSS to create responsive pages and components.

docs/layout/media.md

@@ -1,6 +1,7 @@
 ---
 layout: page
 title: Media
+group: layout
 ---
 
 Abstract object styles for building custom components (like blog comments, Tweets, etc) that feature a left- or right-aligned image alongside textual content.

docs/layout/responsive-utilities.md

@@ -1,6 +1,7 @@
 ---
 layout: page
 title: Responsive utilities
+group: layout
 ---
 
 For faster mobile-friendly development, use these utility classes for showing and hiding content by device via media query. Also included are utility classes for toggling content when printed.

docs/layout/scaffolding.md

@@ -1,6 +1,7 @@
 ---
 layout: page
 title: Scaffolding
+group: layout
 ---
 
 The scaffolding of Bootstrap refers to our general approach to building the project. It outlines the basic document requirements and project dependencies.