DOCS-15602 Recipient shard may incorrectly return 0 milliseconds remaining in resharding (#2228)

Author: jmd-mongo

source/reference/command/serverStatus.txt

@@ -4737,14 +4737,16 @@ shardingStatistics
 .. serverstatus:: shardingStatistics.resharding.oldestActive.coordinatorAllShardsHighestRemainingOperationTimeEstimatedMillis
 
    Calculated across all shards, the highest estimate of the number of
-   seconds remaining. 
+   seconds remaining. If the time estimate cannot be computed, the 
+   value is set to -1.
 
    .. versionadded:: 6.1
 
 .. serverstatus:: shardingStatistics.resharding.oldestActive.coordinatorAllShardsLowestRemainingOperationTimeEstimatedMillis
 
    Calculated across all shards, the lowest estimate of the number of
-   seconds remaining. 
+   seconds remaining. If the time estimate cannot be computed, the 
+   value is set to -1.
 
    .. versionadded:: 6.1
 

source/reference/operator/aggregation/currentOp.txt

@@ -1562,7 +1562,8 @@ relevant for the operation:
    :ref:`resharding operation <sharding-resharding>`. The time is set to
    -1 when a new resharding operation starts.
 
-   Only present when a resharding operation is taking place.
+   Only present when a resharding operation is taking place. This 
+   field may not be present if an estimate cannot not be computed.
 
    .. versionadded:: 5.0