Update content/hardware/10.mega/shields/giga-display-shield/tutorials/09.3d-engine-tutorial/content.md

Co-authored-by: Karl Söderby <35461661+karlsoderby@users.noreply.github.com>

Author: BenjaminDannegard

content/hardware/10.mega/shields/giga-display-shield/tutorials/09.3d-engine-tutorial/content.md

@@ -29,6 +29,8 @@ To install the required libraries for this tutorail, search for **TinyGL**, **LV
 
 The TinyGL library will enable us to run an engine that can render 3D objects on the GIGA Display Shield. TinyGL is based on OpenGL, meaning the objects that we want to be rendered are defined in a `.c` file. Let's take a closer look at these files!
 
+- The source code for this library is available [here](https://github.com/arduino-libraries/TinyGL)
+
 ### A TinyGL Example
 
 Open the example by going to **Files > Examples > TinyGL > Gears** in the Arduino IDE, this will open both the required files in the IDE. You should see a `Gears.ino` and a `gears.c` file as tabs in the IDE. Let's first have a look at the `gears.c` file!