[Sync-EN] Fix the unresolved ZMQ exception entity references

[lacatoire]

Syncs the six reference/zmq/ files with php/doc-en#5776.

• book.xml now includes the five exception class pages, each after the class it belongs to. They existed but were never pulled into the book.
• Each exception page drops the Methods xi:include that pointed at its own class.<name> id, which resolved to nothing since these classes declare no methods.
• The InheritedMethods xi:include points at class.exception instead of class.zmqexception on the four subclasses.
• Each page drops the trailing &reference.zmq.entities.<name>; reference.
• zmqdeviceexception.xml drops the unused xmlns:xlink declaration.

EN-Revision bumped to c517a71287d79c65ea42dff4c6973e22ef5c3bee on the six files.

Fixes: #1676