Issue #3138718 by sja112, longwave, dww, xjm, alexpott: Convert British English spellings to American English, for the umpteenth time

(cherry picked from commit 5a81152270d360dd2e650c760c18f449b6e85f1c)

Author: alexpott

Plugin.php

@@ -103,7 +103,7 @@ public function postCmd(Event $event) {
  }
 
  /**
- * Post package event behaviour.
+ * Post package event behavior.
  *
  * @param \Composer\Installer\PackageEvent $event
  * Composer package event sent on install/update/remove.