Migrate ZFS-* message descriptions (#49)

Prerequisite for changing the URLs in the command outputs from
zfsonlinux.org to openzfs.github.io/openzfs-docs/

Signed-off-by: Ryan Moeller <ryan@iXsystems.com>

docs/msg/ZFS-8000-EY/index.rst

@@ -0,0 +1,79 @@
+..
+   CDDL HEADER START
+
+   The contents of this file are subject to the terms of the
+   Common Development and Distribution License (the "License").
+   You may not use this file except in compliance with the License.
+
+   You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+   or http://www.opensolaris.org/os/licensing.
+   See the License for the specific language governing permissions
+   and limitations under the License.
+
+   When distributing Covered Code, include this CDDL HEADER in each
+   file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+   If applicable, add the following below this CDDL HEADER, with the
+   fields enclosed by brackets "[]" replaced with your own identifying
+   information: Portions Copyright [yyyy] [name of copyright owner]
+
+   CDDL HEADER END
+
+   Portions Copyright 2007 Sun Microsystems, Inc.
+
+.. highlight:: none
+
+Message ID: ZFS-8000-EY
+=======================
+
+ZFS label hostid mismatch
+-------------------------
+
++-------------------------+---------------------------------------------------+
+| **Type:**               | Error                                             |
++-------------------------+---------------------------------------------------+
+| **Severity:**           | Major                                             |
++-------------------------+---------------------------------------------------+
+| **Description:**        | The ZFS pool was last accessed by another system. |
++-------------------------+---------------------------------------------------+
+| **Automated Response:** | No automated response will be taken.              |
++-------------------------+---------------------------------------------------+
+| **Impact:**             | ZFS filesystems are not available.                |
++-------------------------+---------------------------------------------------+
+
+.. rubric:: Suggested Action for System Administrator
+
+The pool has been written to from another host, and was not cleanly
+exported from the other system.  Actively importing a pool on multiple
+systems will corrupt the pool and leave it in an unrecoverable state.
+To determine which system last accessed the pool, run the ``zpool
+import`` command:
+
+::
+
+   # zpool import
+     pool: test
+       id: 14702934086626715962
+    state: ONLINE
+   status: The pool was last accessed by another system.
+   action: The pool can be imported using its name or numeric identifier and
+           the '-f' flag.
+      see: https://openzfs.github.io/openzfs-docs/msg/ZFS-8000-EY
+   config:
+
+           test              ONLINE
+             c0t0d0          ONLINE
+
+   # zpool import test
+   cannot import 'test': pool may be in use from other system, it was last
+   accessed by 'tank' (hostid: 0x1435718c) on Fri Mar  9 15:42:47 2007
+   use '-f' to import anyway
+
+If you are certain that the pool is not being actively accessed by
+another system, then you can use the ``-f`` option to ``zpool import`` to
+forcibly import the pool.
+
+.. rubric:: Details
+
+The Message ID: ``ZFS-8000-EY`` indicates that the pool cannot be
+imported as it was last accessed by another system.  Take the
+documented action to resolve the problem.