Update README.md

Author: kasparsj

README.md

@@ -20,6 +20,8 @@ use Scopus\ScopusApi;
 // replace with your API key
 $apiKey = "114ff0c3b57a0ec62e15efdedefd2e6f";
 $api = new ScopusApi($apiKey);
+
+// Scopus Search API
 $results = $api
     ->query("af-id(60071066)")
     ->start(0)
@@ -31,13 +33,17 @@ var_dump($results);
 
 foreach ($results->getEntries() as $entry) {
     $abstractUrl = $entry->getLinks()->getSelf();
+    
+    // Abstract Retrieval API
     $abstract = $api->retrieve($abstractUrl);
 
     var_dump($abstract);
 
     $authors = $entry->getAuthors();
     foreach ($authors as $author) {
         $authorUrl = $author->getUrl();
+        
+        // Author Retrieval API
         $author = $api->retrieve($authorUrl);
 
         var_dump($author);