clientv3: remove duplicate documentation for Do()

clientv3/kv.go

@@ -51,11 +51,6 @@ type KV interface {
 	// Compact compacts etcd KV history before the given rev.
 	Compact(ctx context.Context, rev int64, opts ...CompactOption) (*CompactResponse, error)
 
-	// Do applies a single Op on KV without a transaction.
-	// Do is useful when declaring operations to be issued at a later time
-	// whereas Get/Put/Delete are for better suited for when the operation
-	// should be immediately issued at time of declaration.
-
 	// Do applies a single Op on KV without a transaction.
 	// Do is useful when creating arbitrary operations to be issued at a
 	// later time; the user can range over the operations, calling Do to