Rex is definitely Perl related. It has extensive documentation on the website.

Unfortunately, the website is very thin on documentation for defining servers. I have already looked through it. Defining servers was only mentioned in passing here.

$PM = "Perl Monk's";
$MCF = "Most Clueless Friar Abbot Bishop Pontiff Deacon Curate Priest Vicar";
$nysus = $PM . ' ' . $MCF;
Click here if you love Perl Monks

The page to which you linked reads fine to me. What is it explicitly that you are looking for which isn't covered?

Update: There's a new issue for this very topic.

If you mean it's the second time today, it's because the same person has asked two different questions, albeit not in a very efficient way, for example linking to the thing in question. Rex is the top result for a metacpan search, ditto duck duck go, when searching using perl context. I wouldn't have approved the previous question unmoderated had it been Off Topic for the site.