Headless renderer example has been added (#13006)

# Objective

Fixes #11457.
Fixes #22.

## Solution

Based on [another headless
application](https://github.com/richardanaya/headless/)

---

## Changelog

- Adopted to bevy 0.14

---------

Co-authored-by: BD103 <59022059+BD103@users.noreply.github.com>
Co-authored-by: François Mockers <francois.mockers@vleue.com>

Author: 3 people

Cargo.toml

@@ -1274,6 +1274,17 @@ description = "An application that runs with default plugins and displays an emp
 category = "Application"
 wasm = false
 
+[[example]]
+name = "headless_renderer"
+path = "examples/app/headless_renderer.rs"
+doc-scrape-examples = true
+
+[package.metadata.example.headless_renderer]
+name = "Headless Renderer"
+description = "An application that runs with no window, but renders into image file"
+category = "Application"
+wasm = false
+
 [[example]]
 name = "without_winit"
 path = "examples/app/without_winit.rs"

examples/README.md

@@ -188,6 +188,7 @@ Example | Description
 [Empty](../examples/app/empty.rs) | An empty application (does nothing)
 [Empty with Defaults](../examples/app/empty_defaults.rs) | An empty application with default plugins
 [Headless](../examples/app/headless.rs) | An application that runs without default plugins
+[Headless Renderer](../examples/app/headless_renderer.rs) | An application that runs with no window, but renders into image file
 [Log layers](../examples/app/log_layers.rs) | Illustrate how to add custom log layers
 [Logs](../examples/app/logs.rs) | Illustrate how to use generate log output
 [No Renderer](../examples/app/no_renderer.rs) | An application that runs with default plugins and displays an empty window, but without an actual renderer