documentation: so2: move so2 intro lecture to dedicated so2 dir

Signed-off-by: Octavian Purdila <tavi@cs.pub.ro>

Author: tavip

Documentation/teaching/so2/index.rst

@@ -7,7 +7,7 @@ Operating Systems 2
    :caption: Lectures
    :maxdepth: 1
 
-   ../lectures/so2.cs.pub.ro.rst
+   lec1-intro.rst
 
 .. toctree::
    :caption: Labs