Update dRAID short feature description

The documentation describes dRAID as a distributed spare, not
parity, RAID implementation.  Update the short feature description
to match the rest of the documentation.

Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #11229

module/zcommon/zfeature_common.c

@@ -591,7 +591,7 @@ zpool_feature_init(void)
 	}
 
 	zfeature_register(SPA_FEATURE_DRAID,
-	    "org.openzfs:draid", "draid", "Support for distributed parity RAID",
+	    "org.openzfs:draid", "draid", "Support for distributed spare RAID",
 	    ZFEATURE_FLAG_MOS, ZFEATURE_TYPE_BOOLEAN, NULL);
 }