DOCS-2708: fixing missing word

Author: Sam Kleinman

source/core/sharding-introduction.txt

@@ -222,6 +222,6 @@ Adding a shard to a cluster creates an imbalance  since the new
 shard has no chunks. While MongoDB begins migrating data to the new
 shard immediately, it can take some time before the cluster balances.
 
-When removing a shard, the balancer migrates all chunks from to other
+When removing a shard, the balancer migrates all chunks from a shard to other
 shards. After migrating all data and updating the meta data, you can
 safely remove the shard.