Docs are generated for Mongoose

Comments in headers are changed a bit: removed adoc-specific stuff,
markdown is used instead

PUBLISHED_FROM=9242cce85cc52a47a197d377e7e23804721a6bb5

docs/items.json

@@ -1,6 +1,8 @@
 {
   "items": [
     { "type": "section", "name": "usage-example" },
-    { "type": "section", "name": "design-concept" }
+    { "type": "section", "name": "design-concept" },
+    { "type": "section", "name": "build-options" },
+    { "type": "flat_sections_set", "name": "c-api" }
   ]
 }