shaders usage

src/fyrox/rendering/shaders.md

@@ -105,6 +105,45 @@ Shader has rigid structure that could be described in this code snippet:
 )
 ```
 
+The engine can load such shaders if you save it in a file with `.shader` extension. After that, you can assign
+the shader to your material in the Material Editor:
+
+![shader](./shader.png)
+
+Alternatively, you can load the shader from code. To do this, you can use this code:
+
+```rust ,no_run
+# extern crate fyrox;
+# use fyrox::{
+#     asset::manager::ResourceManager,
+#     material::shader::{Shader, ShaderResource},
+# };
+# 
+fn load_shader(resource_manager: &ResourceManager) -> ShaderResource {
+    resource_manager.request::<Shader, _>("path/to/my/cool.shader")
+}
+```
+
+After that you can use the shader to build a material from it:
+
+```rust ,no_run
+# extern crate fyrox;
+# use fyrox::{
+#     asset::manager::ResourceManager,
+#     material::{shader::Shader, Material, SharedMaterial},
+# };
+# 
+fn create_material(resource_manager: &ResourceManager) -> SharedMaterial {
+    let shader = resource_manager.request::<Shader, _>("path/to/my/cool.shader");
+    SharedMaterial::new(Material::from_shader(
+        shader,
+        Some(resource_manager.clone()),
+    ))
+}
+```
+
+This material instance can be used for rendering. For example, you can assign it a surface of some mesh.
+
 ## Properties
 
 Property is a named variable of some type. Properties are directly tied with the uniforms in the sub-shaders,