Remove unused DOCTYPE from odk/examples xcu file
The declared entities have apparently never been referenced ever since the
file's introduction in
9fa09d43d0dc0ec0ac71bad31b85ce7fc302ee90 "INTEGRATION:
CWS sdkinspector2". (And at least xmlreader skips and ignores the content of
such document type declarations anyway.)
Change-Id: I8263200f52bb5f1692090995574619f9c0ec478f
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/117658
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>