fix typo

src/main.cpp

@@ -224,7 +224,7 @@ int main(int argc, char** argv) {
   CLI::App* generate =
       app.add_subcommand(
              "generate",
-             "Generate test path using a transition coverage criteria")
+             "Generate test paths using a transition coverage criteria")
           ->fallthrough();
 
   std::string obs_file;