Docs are generated for Mongoose

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

PUBLISHED_FROM=9242cce85cc52a47a197d377e7e23804721a6bb5

docs/build-options/items.json

@@ -0,0 +1,9 @@
+{
+  "items": [
+    { "type": "markdown", "name": "intro.md" },
+    { "type": "markdown", "name": "enabling-flags.md" },
+    { "type": "markdown", "name": "disabling-flags.md" },
+    { "type": "markdown", "name": "platform-spec.md" },
+    { "type": "markdown", "name": "tunables.md" }
+  ]
+}