Update README.md

README.md

@@ -8,8 +8,13 @@ positional arguments:
 
 optional arguments:
   -h, --help           show this help message and exit
+  
   -a, --all            All LCM nodes are considered
+  
   -n NODE [NODE ...]   Select one or more nodes (at least one)
+  
   -1, --lcm1           LCM1 nodes are considered
+  
   -2, --lcm2           LCM2 nodes are considered
+  
   -v, --version        Print program version