added resource explaining xv6 code for OSTEP

coursepages/ostep/README.md

@@ -144,7 +144,9 @@ The xv6 authors provide a [book](https://pdos.csail.mit.edu/6.828/2018/xv6/book-
 
 However, that book glosses over a lot of the details in the code that you might find challenging, including the advanced C features used, the x86 architecture- specific instructions, and the concurrency aspects (if you haven't finished that section of OSTEP before starting the xv6 projects). To solve this problem, we provide an [annotated guide to xv6](https://github.com/palladian1/xv6-annotated) that goes over the entire xv6 code and analyzes it line-by-line with explanations of the C features, hardware specs, and x86 conventions used. That means it's longer than the official xv6 book, so you don't have to read all of it (and you can probably skip the optional sections unless you care about device drivers), but you can use it as a reference if you're scratching your head about some part of the code.
 
-Also [here](https://www.youtube.com/playlist?list=PLbtzT1TYeoMhTPzyTZboW_j7TPAnjv9XB) is an excellent video series walking through much of the xv6 code.
+[Here](https://github.com/YehudaShapira/xv6-explained) is another in-depth explanation of the xv6 code.
+
+Also [here](https://www.youtube.com/playlist?list=PLbtzT1TYeoMhTPzyTZboW_j7TPAnjv9XB) is an excellent video series walking through much of the xv6 code, and 
 
 ### Miscellaneous