Fix commands for fetchmail/procmail

[MichiK]

The examples are missing zammad run before the rails command.

See zammad/zammad#2791.

[monotek]

Zammad command is not available for everyone. It only exists if you install from DEB or RPM package.

So the commands are correct, iof you installed from source.

Therefore both commands should be in the docs...

[MrGeneration]

Personally I'd prefer to keep redundant information at a minimum, would it be "bad" if we'd link to the following page saying "to learn how to run Zammad commands see xyz" ?

We got this covered quite detailed here: https://docs.zammad.org/en/latest/admin-console.html

[MrGeneration]

I'll be closing this pull request as it didn't move up to now.
However, your feedback isn't lost - to keep the commit history clean I added the suggestions I provided here on the following merge request.
#52

I hope you're okay with this compriomise.