set site name value back to system.site on form submit

src/Form/ModuleConfigurationForm.php

@@ -220,6 +220,8 @@ class ModuleConfigurationForm extends ConfigFormBase {
    */
   public function submitForm(array &$form, FormStateInterface $form_state) {
     $values = $form_state->getValues();
+    
+    //set config values unique to this module
     $this->config('wcm8_siteinfo.settings')
       ->set('prefix', $values['prefix'])
       ->set('admin_link', $values['admin_link'])
@@ -240,8 +242,12 @@ class ModuleConfigurationForm extends ConfigFormBase {
       ->set('instagram', $values['instagram'])
       ->set('photos', $values['photos'])
       ->save();
-
+      
+      //set site name value back to system.site
+      $this->configFactory->getEditable('system.site')
+        ->set('name', $values['site_name'])
+        ->save();
+      
     parent::submitForm($form, $form_state);
   }
-
-}
\ No newline at end of file
+}