docs: rename libs xml/version.xml to xml/version-utils.xml

It seems that gtk-docs stuff is confused when we use version.xml
(package version) and xml/version.xml (library version functions).

Signed-off-by: Karel Zak <kzak@redhat.com>
libsmartcols: fix docs

Signed-off-by: Karel Zak <kzak@redhat.com>