[#1349] node: Evacuate objects without setting mode to MAINTENANCE

Signed-off-by: Anton Nikiforov <an.nikiforov@yadro.com>

docs/evacuation.md

@@ -10,6 +10,12 @@ First of all, by the evacuation the data is transferred to other shards of the s
 
 Only one running evacuation process is allowed on the node at a time.
 
+It is not necessary to turn maintenance mode on storage node.
+
+Once evacuation from shard started, it is impossible to read data from it via public API, except the case when evacuation stopped manually or node restarted.
+
+Because it is necessary to prevent removing by policer objects with policy `REP 1 ...` from remote node during evacuation.
+
 `frostfs-cli` utility is used to manage evacuation.
 
 ## Commands