Fixed some bugs in Zend\Config\Reader code examples

[Martin-P]

This comment mentions a bug in the Zend\Config\Reader\XML code sample:

I think on the example for XML, it should be
echo $data['database']['params']['dbname']['value']; // prints "dbproduction"
not
echo $data['database']['params']['dbname']; // prints "dbproduction"
Also the XML has an excess encoding="utf-8"?>?> --> excess

Fixed those bugs and added some missing semicolons in the code samples.

[Ocramius]

Fixed in #1377