fix typo found by Lukas in older release notes too
fix typo found by Lukas in older release notes too

psiroky/optaplanner-website,droolsjbpm/optaplanner-website,oskopek/optaplanner-website,droolsjbpm/optaplanner-website,oskopek/optaplanner-website,bibryam/optaplanner-website,bibryam/optaplanner-website,oskopek/optaplanner-website,bibryam/optaplanner-website,droolsjbpm/optaplanner-website,psiroky/optaplanner-website,psiroky/optaplanner-website