docs: Update documentation and Doxygen documentation generation
diff --git a/ndn.cxx/blob.h b/ndn.cxx/blob.h
index 4b488b3..1b1aa2d 100644
--- a/ndn.cxx/blob.h
+++ b/ndn.cxx/blob.h
@@ -20,6 +20,7 @@
 NDN_NAMESPACE_BEGIN
 
 /**
+ * @ingroup ndn-cxx
  * @brief Class representing a general-use binary blob
  */
 class Blob
diff --git a/ndn.cxx/detail/error.h b/ndn.cxx/detail/error.h
index a1f1e34..db6b751 100644
--- a/ndn.cxx/detail/error.h
+++ b/ndn.cxx/detail/error.h
@@ -35,6 +35,10 @@
 
 NDN_NAMESPACE_BEGIN
 
+/**
+ * @ingroup ndn-cxx
+ * @brief Namespace holding all errors from NDN.cxx API
+ */
 namespace error
 {
 
diff --git a/ndn.cxx/exclude.h b/ndn.cxx/exclude.h
index 8315f34..fcdcbb3 100644
--- a/ndn.cxx/exclude.h
+++ b/ndn.cxx/exclude.h
@@ -19,6 +19,7 @@
 NDN_NAMESPACE_BEGIN
 
 /**
+ * @ingroup ndn-cxx
  * @brief Class to represent Exclude component in NDN interests
  */
 class Exclude : public SimpleRefCount<Exclude>
diff --git a/ndn.cxx/name-component.h b/ndn.cxx/name-component.h
index 7f523e0..0de0442 100644
--- a/ndn.cxx/name-component.h
+++ b/ndn.cxx/name-component.h
@@ -18,6 +18,7 @@
 namespace name {
 
 /**
+ * @ingroup ndn-cxx
  * @brief Class to representing binary blob of NDN name component
  *
  * This class is based on Blob (std::vector<char>) and just provides several helpers
diff --git a/ndn.cxx/name.h b/ndn.cxx/name.h
index 8731323..731202d 100644
--- a/ndn.cxx/name.h
+++ b/ndn.cxx/name.h
@@ -23,6 +23,7 @@
 NDN_NAMESPACE_BEGIN
 
 /**
+ * @ingroup ndn-cxx
  * @brief Class for NDN Name
  */
 class Name : public SimpleRefCount<Name>
diff --git a/ndn.cxx/ndn-api-face.h b/ndn.cxx/ndn-api-face.h
index 78f482a..ac735c9 100644
--- a/ndn.cxx/ndn-api-face.h
+++ b/ndn.cxx/ndn-api-face.h
@@ -37,9 +37,16 @@
 class ApiFacePriv;
 
 /**
- * \ingroup sync
- * @brief A handler for NDN; clients of this code do not need to deal
- * with NDN API directly
+ * @ingroup ndn
+ * @defgroup ndn-cxx NDN.cxx API
+ */
+
+/**
+ * @ingroup ndn-face
+ * @ingroup ndn-cxx
+ * @brief An application NDN face, providing richer API interface, compared to ndn::AppFace
+ *
+ * @see ndn::AppFace
  */
 class ApiFace
   : public ns3::ndn::Face