oe-setup-builddir: update YP docs and OE URLs

This updates the link to the YP docs
and proposes to access the OE website through https

Signed-off-by: Michael Opdenacker <michael.opdenacker@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 87686233)
Signed-off-by: Steve Sakoman <steve@sakoman.com>