verify-bashisms: point out where to get checkbashisms.pl
The current SourceForge project seems to be unmaintained (last release
2.0.0.2 from 2015) while the copy used by Debian is quite active (last
commit 2016-09-30).
Ideally, checkbashisms.pl should get installed automatically via a
recipe, but for now at least provide the link for manual installation.
Signed-off-by: Patrick Ohly <patrick.ohly@intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
