Fix name in list of features (#2438)

# Objective

- Fix the name of the `bevy_dynamic_plugin` feature in the list of features

## Solution

- Remove the letter "s" 😶

Author: tsoutsman

docs/cargo_features.md

@@ -5,7 +5,7 @@
 |feature name|description|
 |-|-|
 |bevy_audio|Audio support. Support for all audio formats depends on this.|
-|bevy_dynamic_plugins|Plugins for dynamic loading (libloading).|
+|bevy_dynamic_plugin|Plugin for dynamic loading (libloading).|
 |bevy_gilrs|Adds gamepad support.|
 |bevy_gltf|[glTF](https://www.khronos.org/gltf/) support.|
 |bevy_winit|GUI support.|