support the new frontmatter props

Author: sarahs

lib/frontmatter.js

@@ -126,6 +126,46 @@ const schema = {
         name: { type: 'string' },
         URL: { type: 'string' }
       }
+    },
+    // Child links specified on any TOC page
+    children: {
+      type: 'array'
+    },
+    // External products specified on the homepage
+    externalProducts: {
+      type: 'object',
+      properties: {
+        cli: { 
+          type: 'object',
+          required: true,
+          properties: {
+            id: { type: 'string', required: true },
+            name: { type: 'string', required: true },
+            href: { type: 'string', format: 'url', required: true },
+            external: { type: 'boolean', required: true },
+          }
+        },
+        atom: { 
+          type: 'object',
+          required: true,
+          properties: {
+            id: { type: 'string', required: true },
+            name: { type: 'string', required: true },
+            href: { type: 'string', format: 'url', required: true },
+            external: { type: 'boolean', required: true },
+          }
+        },
+        electron: { 
+          type: 'object',
+          required: true,
+          properties: {
+            id: { type: 'string', required: true },
+            name: { type: 'string', required: true },
+            href: { type: 'string', format: 'url', required: true },
+            external: { type: 'boolean', required: true },
+          }
+        }
+      }
     }
   }
 }