doc: clarify tutorial error section
doc: clarify tutorial error section

Signed-off-by: Davide "FunkyAss" Del Zompo <c04902a01a5473de14074df67901f06c72295496@gmail.com>
Reviewed-by: Andreas Schneider <5be00ddc76278cf6077f5047ca3384a88460c671@cryptomilk.org>
(cherry picked from commit bb197de75dc283eb0047e16f107c2441e957ea4f)

mwgoldsmith/libssh,mwgoldsmith/ssh,mwgoldsmith/libssh,mwgoldsmith/libssh,mwgoldsmith/libssh,mwgoldsmith/ssh,mwgoldsmith/ssh,mwgoldsmith/ssh