security: Add doxygen comments

Change-Id: Ieafe4d13513e626d84ef9e621694f69844785018
diff --git a/src/security/sec-rule-relative.cpp b/src/security/sec-rule-relative.cpp
index cdfdeac..db3e653 100644
--- a/src/security/sec-rule-relative.cpp
+++ b/src/security/sec-rule-relative.cpp
@@ -18,8 +18,7 @@
 
 using namespace std;
 
-namespace ndn
-{
+namespace ndn {
 
 SecRuleRelative::SecRuleRelative (const string& dataRegex, const string& signerRegex, const string& op, 
                                   const string& dataExpand, const string& signerExpand, bool isPositive)
@@ -111,4 +110,4 @@
     return true;
 }
 
-}//ndn
+} // namespace ndn