documentation: Add class description.
diff --git a/ndn-cpp/security/identity/identity-manager.hpp b/ndn-cpp/security/identity/identity-manager.hpp
index 4f4c8c2..2db82b1 100644
--- a/ndn-cpp/security/identity/identity-manager.hpp
+++ b/ndn-cpp/security/identity/identity-manager.hpp
@@ -13,6 +13,9 @@
namespace ndn {
+/**
+ * An IdentityManager is the interface of operations related to identity, keys, and certificates.
+ */
class IdentityManager {
public:
IdentityManager(const ptr_lib::shared_ptr<PrivateKeyStorage> &privateKeyStorage)