Improve upgrade doc (#980)

website/content/usage/upgrade.md

@@ -8,11 +8,11 @@ Use one of the following methods (depending on the changes) to upgrade a cluster
 
 Use the following procedure to rotate all cluster nodes, one server at a time:
 
-1. Add a new servers to the cluster with a configuration that joins them to the existing cluter.
-1. Stop dkron service in one of the old servers, if it was the leader allow a new leader to be ellected, note that it is better to remove the current leader at the end, to ensure a leader is elected between the new nodes.
-1. Use `dkron raft list-peers` to list current cluster nodes
-1. Use `dkron raft remove-peer` to forcefully remove the old server
-1. Repeat steps util all old cluster nodes has been rotated
+1. Add a new server to the cluster with a configuration that joins them to the existing cluster.
+1. Stop dkron service on one of the old servers, if it was the leader allow a new leader to be elected. Note that it is better to remove the current leader at the end, to ensure a leader is elected from the new nodes.
+1. Use `dkron raft list-peers` to list current cluster nodes.
+1. Use `dkron raft remove-peer` to forcefully remove the old server.
+1. Repeat steps above until all old cluster nodes have been upgraded.
 
 ### Backup & Restore