security: Add doxygen comments

Change-Id: Ieafe4d13513e626d84ef9e621694f69844785018
diff --git a/src/security/signature-sha256-with-rsa.hpp b/src/security/signature-sha256-with-rsa.hpp
index b1dd6e1..c9db4a3 100644
--- a/src/security/signature-sha256-with-rsa.hpp
+++ b/src/security/signature-sha256-with-rsa.hpp
@@ -5,8 +5,8 @@
  * See COPYING for copyright and distribution information.
  */
 
-#ifndef NDN_SIGNATURE_SHA256_WITH_RSA_HPP
-#define NDN_SIGNATURE_SHA256_WITH_RSA_HPP
+#ifndef NDN_SECURITY_SIGNATURE_SHA256_WITH_RSA_HPP
+#define NDN_SECURITY_SIGNATURE_SHA256_WITH_RSA_HPP
 
 #include "../data.hpp"
 #include "../encoding/tlv.hpp"
@@ -62,4 +62,4 @@
 
 } // namespace ndn
 
-#endif
+#endif //NDN_SECURITY_SIGNATURE_SHA256_WITH_RSA_HPP