[Serializer] Wrong default values in ehe `XmlEncoder` context options array

[afatartmajeur]

https://symfony.com/doc/current/components/serializer.html#the-xmlencoder-context-options

In the array the default values for xml_version says 1.1 and xml_encoding says utf-8, but when I use the encode() method, the xml goes out in 1.0 version and no encoding is specified.

I had a problem with encoding accented characters that got translated in hex (É, ï, etc.) until I specified the xml_encoding in the context. The array is misleading, I thought at first that I didn't need to add the encoding because it was telling me that default was what I was utf-8.
Plus, in the page there are examples of the use of the encode() method that seems to be in version 1.0 by default, so it confirms the problem.

Maybe other default values are wrong in the array, I didn't check them.

[alexandre-daubois]

I opened a PR for this typo. However, about the encoding, it seems that the default one is actually UTF-8. Maybe this depends on your PHP installation?