docs/163007: Fix typo on zpool(8)

[Sergey V. Dyatko]

>Number:         163007
>Category:       docs
>Synopsis:       Fix typo on zpool(8)
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-doc
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          doc-bug
>Submitter-Id:   current-users
>Arrival-Date:   Fri Dec 02 05:30:09 UTC 2011
>Closed-Date:
>Last-Modified:
>Originator:     Sergey V. Dyatko
>Release:        head
>Organization:
>Environment:
FreeBSD laptop.minsk.domain 10.0-CURRENT FreeBSD 10.0-CURRENT #10 r227991M: Sat Nov 26 21:09:20 FET 2011     root at laptop.minsk.domain:/usr/obj/usr/src/sys/b450  amd64

>Description:
dublicate 'cannot be' in description for cache vdev
>How-To-Repeat:

>Fix:
[tiger at laptop]~%diff -Nura zpool.8.orig zpool.8

--- zpool.8.orig        2011-12-02 08:20:59.011383988 +0300
+++ zpool.8     2011-12-02 08:21:34.081379965 +0300
@@ -261,8 +261,8 @@
 \fB\fBcache\fR\fR
 .ad
 .RS 10n
-A device used to cache storage pool data. A cache device cannot be cannot be
-configured as a mirror or \fBraidz\fR group. For more information, see the
+A device used to cache storage pool data. A cache device cannot be configured 
+as a mirror or \fBraidz\fR group. For more information, see the
 "Cache Devices" section.
 .RE


>Release-Note:
>Audit-Trail:
>Unformatted: