Document SparesMissing and DeviceDisappeared/WrongLevel

Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>

ChangeLog

@@ -1,6 +1,7 @@
 Changes Prior to this release
     -   Don't use 'lstat' to check for blockdevices, use stat.
     -   Document --size=max option for --grow
+    -   Document SparesMissing event and DeviceDisappeared/WrongLevel
 	
 Changes Prior to 1.11.0 release
     -   Fix embarassing bug which causes --add to always fail.

mdadm.8

@@ -1057,6 +1057,16 @@ The different events are:
 An md array which previously was configured appears to no longer be
 configured.
 
+If
+.I mdadm
+was told to monitor an array which is RAID0 or Linear, then it will
+report
+.B DeviceDisappeared
+with the extra information
+.BR Wrong-Level .
+This is because RAID0 and Linear do not support the device-failed,
+hot-spare and resync operations which are monitored.
+
 .TP
 .B RebuildStarted
 An md array started reconstruction.
@@ -1108,6 +1118,18 @@ A spare drive has been moved from one array in a
 .B spare-group
 to another to allow a failed drive to be replaced.
 
+.TP
+.B SparesMissing
+If
+.I mdadm
+has been told, via the config file, that an array should have a certain
+number of spare devices, and
+.I mdadm
+detects that it has fewer that this number when it first sees the
+array, it will report a
+.B SparesMissing
+message.
+
 .TP
 .B TestMessage
 An array was found at startup, and the