docs: wrote Doxygen comments for all files

refs: #4118

Change-Id: Ib0e7f1926cdabcca5aa401b59b24519412a099f7
diff --git a/src/adjacent.cpp b/src/adjacent.cpp
index 55ddff5..78c71b5 100644
--- a/src/adjacent.cpp
+++ b/src/adjacent.cpp
@@ -17,15 +17,15 @@
  * You should have received a copy of the GNU General Public License along with
  * NLSR, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
  **/
+
+#include "adjacent.hpp"
+#include "logger.hpp"
+
 #include <iostream>
 #include <string>
 #include <cmath>
 #include <limits>
 
-
-#include "adjacent.hpp"
-#include "logger.hpp"
-
 namespace nlsr {
 
 INIT_LOGGER("Adjacent");