docs/9.1/static/kernel-resources.html needs updating for NetBSD

Hello

The NetBSD paragraph about setting the amount of shared memory for
NetBSD in
http://www.postgresql.org/docs/9.1/static/kernel-resources.html is outdated.

Since NetBSD 5.0 the shared memory size settings can be changed via the
sysctl interface. For example, to allow 16 MB:
# sysctl -w kern.ipc.shmmax=16777216
In addition these settings can be preserved between reboots in the file
/etc/sysctl.conf.


This part is still valid
"
You might also want to configure your kernel to lock shared memory into
RAM and prevent it from being paged out to swap. This can be
accomplished using the sysctl setting kern.ipc.shm_use_phys.
"

Manu