Example to show usage of submit_and_watch_extrinsic_until_without_event

[haerdib]

Create an example to show the usage of this function (if there's a reasonable example use case)

According to #615 (comment):

Not showing any examples is just a way of forcing the user not to use it. Is that really what we want?
I'm not sure the comments are clear enough. Because we're talking about an error when an extrinsic has failed on the chain, and not an event, the user may think that submit_and_watch_extrinsic_until_without_event informs her when an extrinsic fails on the chain. Without studying the code, they may miss this point.
Maybe add an example check_extrinsic_without_events similar to check_extrinsic_events? We could do it in another issue. Maybe I'm too picky, so it's up to you to decide.