Update building_block_commands.md

docs/bot_tutorial/building_block_commands.md

@@ -58,7 +58,7 @@ def on_tag_command(self, event, name, value=None):
 ```
 
 A different way of adding arguments to a command is by using argparse.ArgumentParser. With argparser it's easier to create more complicated commands with many options or flags.
-Right here, we'll recreate our math add command, but using argparser.
+Right here, we'll recreate our math add command, but using argparser. More info on argparser and the add_argument() method can be found [here](https://docs.python.org/2/library/argparse.html#the-add-argument-method)
 ```py
 @Plugin.command('add', parser=True, group='math')
 @Plugin.parser.add_argument('a', type=int)