Preauth documentation improvements

[riogd]

There are some confusing bits when dealing with preauth based on documentation examples and actual required syntax.

In the wiki entry for Preauth the detail of the url parameters as well as the description of each parameter orders "timestamp" before "expires" (in both places). This same ordering is used under the "gdpa" section of the Zmprov wiki page. It is indeed the order expected by the gdpa zmprov command.

The room for improvement comes from the fact that it is NOT the order expected by the Preauth URL Interface. It is true that in the Preauth wiki page reminds that:

1. concat the values for account, by, expires, timestamp together
(in that order, order is definitely important!), separated by "|"

However that introduces a new and different order, inconsistent with all other ordering, now saying that "expires" comes before "timestamp".
Since the wiki page appears to be managed by Zimbra Staff I thought I would let one of them make whatever changes they deemed necessary.

Cheers,

RioGD