6781 zpool man page needs updated to remove duplicate entry of "cannot be" where it discusses cache devices
illumos/illumos-gate@e4cb59f791c5c6dea7ad4caa6dee845024ce71ef
https://github.com/illumos/illumos-gate/commit/e4cb59f791c5c6dea7ad4caa6dee845024ce71ef
https://www.illumos.org/issues/6781
cache A device used to cache storage pool data. A cache device cannot be cannot be configured as a mirror or raidz group. For more information, see the "Cache Devices" section. needs changed to cache A device used to cache storage pool data. A cache device cannot be configured as a mirror or raidz group. For more information, see the "Cache Devices" section.
Reviewed by: Toomas Soome <tsoome@me.com>
Reviewed by: Robert Mustacchi <rm@joyent.com>
Approved by: Matthew Ahrens <mahrens@delphix.com>
Author: Alexander Pyhalov <apyhalov@gmail.com>