man: zpool-add.8: import examples from zpool.8

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #13228

man/man8/zpool-add.8

@@ -25,7 +25,7 @@
 .\" Copyright 2017 Nexenta Systems, Inc.
 .\" Copyright (c) 2017 Open-E, Inc. All Rights Reserved.
 .\"
-.Dd May 27, 2021
+.Dd March 16, 2022
 .Dt ZPOOL-ADD 8
 .Os
 .
@@ -93,6 +93,29 @@ The only property supported at the moment is
 .Sy ashift .
 .El
 .
+.Sh EXAMPLES
+.\" These are, respectively, examples 5, 13 from zpool.8
+.\" Make sure to update them bidirectionally
+.Ss Example 1 : No Adding a Mirror to a ZFS Storage Pool
+The following command adds two mirrored disks to the pool
+.Ar tank ,
+assuming the pool is already made up of two-way mirrors.
+The additional space is immediately available to any datasets within the pool.
+.Dl # Nm zpool Cm add Ar tank Sy mirror Pa sda sdb
+.
+.Ss Example 2 : No Adding Cache Devices to a ZFS Pool
+The following command adds two disks for use as cache devices to a ZFS storage
+pool:
+.Dl # Nm zpool Cm add Ar pool Sy cache Pa sdc sdd
+.Pp
+Once added, the cache devices gradually fill with content from main memory.
+Depending on the size of your cache devices, it could take over an hour for
+them to fill.
+Capacity and reads can be monitored using the
+.Cm iostat
+subcommand as follows:
+.Dl # Nm zpool Cm iostat Fl v Ar pool 5
+.
 .Sh SEE ALSO
 .Xr zpool-attach 8 ,
 .Xr zpool-import 8 ,

man/man8/zpool.8

@@ -231,6 +231,7 @@ Invalid command line options were specified.
 .
 .Sh EXAMPLES
 .\" Examples 1, 2, 3, 4, 11, 12 are shared with zpool-create.8.
+.\" Examples 5, 13 are shared with zpool-add.8.
 .\" Make sure to update them bidirectionally
 .Ss Example 1 : No Creating a RAID-Z Storage Pool
 The following command creates a pool with a single raidz root vdev that