docs: add slot readme example

Author: dcoa

src/plugin-slots/LanguageSelectorSlot/README.md

@@ -11,3 +11,28 @@ This slot is used to repace/modify/hide the language selector in the footer.
 
 ## Example
 
+![Screenshot default language selector](images/default_lang_selector.png)
+
+Use the following snipped to hide the selector
+
+![Screenshot hidden language selector](images/hidden_lang_selector.png)
+
+```jsx
+import { DIRECT_PLUGIN, PLUGIN_OPERATIONS } from '@openedx/frontend-plugin-framework';
+
+const config = {
+  pluginSlots: {
+    'org.openedx.frontend.layout.footer_lang_selector.v1': {
+      plugins: [
+        {
+          // Hide the default footer
+          op: PLUGIN_OPERATIONS.Hide,
+          widgetId: 'default_contents',
+        },
+      ]
+    }
+  },
+}
+
+export default config;
+```