add the intro video

Author: pkucmus

docs/assets/fhd.jpg

@@ -3,7 +3,9 @@ title: Introduction
 ---
 # EVA <sub><sup>2.1.0</sup></sub>
 
-![](assets/banner.png)
+<iframe id="player" type="text/html" width="800" height="480"
+  src="http://www.youtube.com/embed/fOFlQ7dKGFQ?enablejsapi=1&origin=https://eva-3d.github.io/eva-main/"
+  frameborder="0"></iframe>
 
 ## Platform
 

docs/assets/fhd.png

@@ -12,7 +12,7 @@ The parts are not oriented in the print orientation. I am currently unavailable
 
 Unless specified the parts require **no supports**. If your print orientation required supports then you oriented the part wrong :)
 
-## Handling ex nuts
+## Handling hex nuts
 
 To properly insert a hex nut into a printed part you need to take a short screw, thread it through the hole, put the nut in, drive the nut untill it's properly sitting in it's place and finally remove the short screw. **This is very important** and will allow for the nut not to bind in the screw threads when you are mid-way through your assembly - when a nut binds the two parts are usually garbage and need to be reprinted.