doc: add dd example for failing disks

* doc/coreutils.texi (dd invocation): Add an example for how to call
dd to save data from a failing disk.  Mention GNU 'ddrescue' as one
of the more specialized tools in such a case.
shuf: convert error diagnostic to lowercase

* src/shuf.c (main): s/No/no/, introduced by commit v8.22-25-g9f60f37.
* NEWS: Also adjust the NEWS for that recent commit to make it
clear this was new bug rather than a regression.

Prompted by the syntax-check rule sc_error_message_uppercase