Fix typo in upgrade.html
Reviewers: Mickael Maison
The 2.7.0 release includes the core Raft implementation specified in
<a href="https://cwiki.apache.org/confluence/display/KAFKA/KIP-595%3A+A+Raft+Protocol+for+the+Metadata+Quorum">KIP-595</a>.
There is a separate "raft" module containing most of the logic. Until integration with the
- controller is complete, there is a standalone server that users can use for testing the p
- erformance of the Raft implementation. See the README.md in the raft module for details
+ controller is complete, there is a standalone server that users can use for testing the
+ performance of the Raft implementation. See the README.md in the raft module for details
</li>
<li>
KIP-651 <a href="https://cwiki.apache.org/confluence/display/KAFKA/KIP-651+-+Support+PEM+format+for+SSL+certificates+and+private+key">adds support</a>
