feat: add README and example images for Extended Profile Fields slot

Author: bra-i-am

src/plugin-slots/ExtendedProfileFieldsSlot/README.md

@@ -0,0 +1,50 @@
+# Extended Profile Fields
+
+### Slot ID: `org.openedx.frontend.profile.extended_profile_fields.v1`
+
+### Slot ID Aliases
+* `extended_profile_fields_slot`
+
+## Description
+
+This slot is used to replace/modify/hide the extended profile fields in the account page.
+
+## Example
+
+> [!NOTE]
+> Take into account that the fields shown in the screenshots come from a [custom NPM Package](https://www.npmjs.com/package/@edunext/frontend-component-extended-fields) 
+
+The following `env.config.jsx` will replace the default custom fields. 
+
+![Screenshot of Default Fields](./images/default_fields.png)
+
+with a custom extended fields component
+
+![Screenshot of Custom Fields](./images/custom_fields.png)
+
+```jsx
+import { DIRECT_PLUGIN, PLUGIN_OPERATIONS } from '@openedx/frontend-plugin-framework';
+
+import { ExtendedProfileFields } from '@organization/frontend-component-extended-fields';
+
+const config = {
+	pluginSlots: {
+		extended_profile_fields_slot: {
+			keepDefault: false,
+			plugins: [
+				{
+                    // Insert a custom ExtendedProfileFields component
+					op: PLUGIN_OPERATIONS.Insert,
+					widget: {
+						id: 'extended_profile_fields',
+						type: DIRECT_PLUGIN,
+						RenderWidget: ExtendedProfileFields,
+					},
+				},
+			],
+		},
+	},
+};
+
+export default config;
+```