Add message for man page to help information.

TODO.md

@@ -4,7 +4,7 @@
   - [X] Add basic functionality.
   - [X] Add more safeguards to avoid bad usage.
   - [X] Create a man page.
-  - [ ] Add more documentation to `help` subcommand.
+  - [X] Add more documentation to `help` subcommand.
   - [X] Properly align output columns from `list` subcommand.
   - [X] Add feature for editing recipe name and description.
     - [X] Name

src/arg_parse.hpp

@@ -79,6 +79,7 @@ static inline void print_help(void) {
 		   "\thelp, -h, --help             Show this help information.\n"
 		   "\tversion, -v, --version       Show version information.\n"
 		   << std::endl;
+	std::cout << "For more information about subcommands, use 'man menu-helper'." << std::endl;
 }
 
 enum cmd_id parse_args(const std::string &cmd);