Fix PHPDocs of GadgetDefinitionContent::getDeletionUpdates

DataUpdate is a specific implementation (currently the only one), while
DeferrableUpdate is the interface. Binding against the interface is
enough, and what the base classes already do.

I'm also removing a line of meaningless documentation. "Creates an
instance of this class" is a general description that is true for all
constructors.

Change-Id: Ia6dc86b078628db5e0ab68ef46bf0396567b767c

includes/GadgetResourceLoaderModule.php

@@ -16,8 +16,6 @@ class GadgetResourceLoaderModule extends ResourceLoaderWikiModule {
 	private $gadget;
 
 	/**
-	 * Creates an instance of this class
-	 *
 	 * @param array $options
 	 */
 	public function __construct( array $options ) {

includes/content/GadgetDefinitionContent.php

@@ -97,7 +97,7 @@ class GadgetDefinitionContent extends JsonContent {
 	/**
 	 * @param WikiPage $page
 	 * @param ParserOutput $parserOutput
-	 * @return DataUpdate[]
+	 * @return DeferrableUpdate[]
 	 */
 	public function getDeletionUpdates( WikiPage $page, ParserOutput $parserOutput = null ) {
 		return array_merge(