Update the YANG module template.

docs/examples/template.yin

 <?xml version="1.0" encoding="utf-8"?>
 <module name="example-n"
-        xmlns="urn:ietf:params:xml:ns:yang:yin:1"
-        xmlns:test="http://example.com/example-n">
+        xmlns="urn:ietf:params:xml:ns:yang:yin:1">
   <yang-version value="1.1"/>
   <namespace uri="http://example.com/example-n"/>
   <prefix value="exn"/>