Remove the shared PERSISTENT_DIR mention introduced by 3954eda78f22
("dev-manual/start.rst: mention that PERSISTENT_DIR should be shared
too"), as it should _not_ be shared.
Instead recommend setting up a hash equivalence server.
(From yocto-docs rev: f9f1c87424d307d2df60024bc448bd6778605cf8)
Signed-off-by: Antonin Godard <antonin.godard@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
853f8bfbb8