un-hide the feathers example (#21463)

# Objective

- Example feathers is hidden, maybe because its experimental
- Other examples are using the experimental feathers feature and are not
hidden

## Solution

- un hide the feathers example

I would like this to be part of the next 0.17 patch, feathers is part of
the release notes, it's a bit sad to not be able to show the example on
the website

Author: mockersf

Cargo.toml

@@ -4719,7 +4719,6 @@ name = "Feathers Widgets"
 description = "Gallery of Feathers Widgets"
 category = "UI (User Interface)"
 wasm = true
-hidden = true
 
 [[example]]
 name = "render_depth_to_texture"

examples/README.md

@@ -551,6 +551,7 @@ Example | Description
 [Directional Navigation](../examples/ui/directional_navigation.rs) | Demonstration of Directional Navigation between UI elements
 [Display and Visibility](../examples/ui/display_and_visibility.rs) | Demonstrates how Display and Visibility work in the UI.
 [Drag to Scroll](../examples/ui/drag_to_scroll.rs) | This example tests scale factor, dragging and scrolling
+[Feathers Widgets](../examples/ui/feathers.rs) | Gallery of Feathers Widgets
 [Flex Layout](../examples/ui/flex_layout.rs) | Demonstrates how the AlignItems and JustifyContent properties can be composed to layout nodes and position text
 [Font Atlas Debug](../examples/ui/font_atlas_debug.rs) | Illustrates how FontAtlases are populated (used to optimize text rendering internally)
 [Ghost Nodes](../examples/ui/ghost_nodes.rs) | Demonstrates the use of Ghost Nodes to skip entities in the UI layout hierarchy