docs(README): add youtube link and short desc

README.md

@@ -7,7 +7,11 @@
 
 *Steel version (PC executable)*
 
-TODO cool image and youtube link
+Discover an engine where user-defined fragment shaders collide to produce stunning visuals.
+
+![](./images/preview.png)
+
+See [1H demo on YouTube](https://youtu.be/HgErrasSs-w)
 
 <!-- omit from toc -->
 ## Table of Contents
@@ -41,7 +45,7 @@ TODO
 ### Prerequisites
 
 | library   | apt            | pacman          |
-| --- | --- | --- |
+| --------- | -------------- | --------------- |
 | libglfw   | libglfw3-dev   | extra/glfw      |
 | libGL     | libgl-dev      | extra/libglvnd  |
 | libasound | libasound2-dev | extra/alsa-lib  |
@@ -116,8 +120,6 @@ options:
 
 > A.K.A Kleπek's shaders
 
-![](./images/preview.png)
-
 ### Sources and Effects
 
 | P     | #     | SRC               | _COL2_            | _COL3_          | _COL4_             | FX               | _COL6_          | _COL7_        | _COL8_         |