add some comments

src/villas-convert.cpp

@@ -51,6 +51,7 @@ int main(int argc, char *argv[])
 	const char *output_format = "villas.human";
 
 	char c, *endptr;
+	/* Parse optional command line arguments */
 	while ((c = getopt(argc, argv, "Vhd:i:o:")) != -1) {
 		switch (c) {
 			case 'V':

src/villas-hook.cpp

@@ -122,6 +122,7 @@ int main(int argc, char *argv[])
 	json_t *cfg_cli = json_object();
 
 	char c, *endptr;
+	/* Parse optional command line arguments */
 	while ((c = getopt(argc, argv, "Vhv:d:f:o:")) != -1) {
 		switch (c) {
 			case 'V':

src/villas-node.cpp

@@ -117,6 +117,8 @@ int main(int argc, char *argv[])
 
 	const char *uri = "opal-shmem.conf";
 #else
+
+	/* Parse optional command line arguments */
 	int c;
 	while ((c = getopt(argc, argv, "hV")) != -1) {
 		switch (c) {

src/villas-pipe.cpp

@@ -255,6 +255,7 @@ int main(int argc, char *argv[])
 
 	json_t *cfg_cli = json_object();
 
+	/* Parse optional command line arguments */
 	int c;
 	char *endptr;
 	while ((c = getopt(argc, argv, "Vhxrsd:l:L:t:f:o:")) != -1) {