added docstring

pet-wrapper-api.py

@@ -194,6 +194,10 @@ class PET(plugin.PluginAbstract):
         return file_dict
 
     def prepare_html_output(self, path_output):
+        """
+        Prepare the HTML output for the plugin in 
+        the result section.
+        """
         result = subprocess.run(
             ["ls", "-la", path_output], capture_output=True, text=True
         )