To disable the sad smiley that appears when a command fails with the default
zshrc, you need to run these two commands:

zstyle ':prompt:grml:right:setup' use-rprompt false
zstyle ':prompt:grml:right:setup' items ''

From the documentation (prompt -h grml) one would think that either would be
sufficient.

In general, the use-rpompt style is unclear.

Suggestions:

1) use-rprompt is removed

2) `zstyle ':prompt:grml:right:setup' items ''` is made sufficient to remove the
sad-smiley

3) The documentation is extended to include an example of how to add and remove
items from the prompt.