Incorrect upper limit of 8k in config file

[DimitriPapadopoulos]

Not sure where the upper limit of 8k comes from:

freeradius-client/tests/docker/radius-clients.conf

Lines 75 to 79 in 5a7c776

	# The shared secret use to "encrypt" and "sign" packets between
	# the NAS and FreeRADIUS. You MUST change this secret from the
	# default, otherwise it's not a secret any more!
	#
	# The secret can be any string, up to 8k characters in length.

As far as I can see, the current maximal length of the shared secret is 256:

freeradius-client/include/freeradius-client.h

Line 61 in 5a7c776

#define MAX_SECRET_LENGTH (16 * 16) /* MUST be multiple of 16 */

[alandekok]

Yes, that needs fixing. Thanks.