Fixing comments

plugin/hello_world/install.php

@@ -1,2 +1,14 @@
 <?php
-/* Script to uninstall the plugin */
+/* PHP code to install the plugin 
+ * For example:
+ * 
+    // To query something to the database
+  
+    $table = Database::get_main_table(TABLE_MAIN_USER); // TABLE_MAIN_USER is a constant check the main/inc/database.constants.inc.php
+    $sql = "SELECT firstname, lastname FROM $table_users ";
+    $users = Database::query($sql); 
+  
+    You can also use the Chamilo classes 
+    $users = UserManager::get_user_list();    
+    
+ */ 

plugin/hello_world/uninstall.php

@@ -1,2 +1,2 @@
 <?php
-/* Script to install the plugin */
+/* PHP code to uninstall the plugin */