Add missing @return to Requirement

even with type hint there should be the full phpdoc to be consistent

Change-Id: I74f2fec23d655deee5704b0ab432cba5c7921ab6

includes/FeatureManagement/Requirement.php

@@ -35,11 +35,13 @@ interface Requirement {
 
 	/**
 	 * Gets the name of the requirement.
+	 * @return string
 	 */
 	public function getName() : string;
 
 	/**
 	 * Gets whether the requirement is met.
+	 * @return bool
 	 */
 	public function isMet() : bool;
 }