Change bruteforce terminal-output

[Tristan-H11]

Is your feature request related to a problem? Please describe.
A user should see something like "please type 'stop' when you think you're PC calculated the attack for long enough". At the moment, a user does not about having to stop manually, if he does not read the wiki.

[Akida31]

The new GD for FE document will define the output of the commands in the long run (currently service bruteforce is on page 74). Please change it there and the new shell (#258) should fix that.

[Tristan-H11]

@Akida31 perfect. Thank you.