frameworks/native: document native types and enums

Change-Id: Id94b610f27b87426abb30e13484cbd16990aa995
diff --git a/include/android/obb.h b/include/android/obb.h
index 65e9b2a..4c6d9d7 100644
--- a/include/android/obb.h
+++ b/include/android/obb.h
@@ -14,6 +14,14 @@
  * limitations under the License.
  */
 
+/**
+ * @addtogroup Storage
+ * @{
+ */
+
+/**
+ * @file obb.h
+ */
 
 #ifndef ANDROID_OBB_H
 #define ANDROID_OBB_H
@@ -25,9 +33,12 @@
 #endif
 
 struct AObbInfo;
+/** {@link AObbInfo} is an opaque type representing information for obb storage. */
 typedef struct AObbInfo AObbInfo;
 
+/** Flag for an obb file, returned by AObbInfo_getFlags(). */
 enum {
+    /** overlay */
     AOBBINFO_OVERLAY = 0x0001,
 };
 
@@ -61,3 +72,5 @@
 #endif
 
 #endif      // ANDROID_OBB_H
+
+/** @} */