Simplify comments to be more concise and student-like

- Removed verbose explanations
- Made comments shorter and more casual
- Focus on key concepts rather than formal descriptions

01/Xor.hdl

@@ -11,7 +11,7 @@ CHIP Xor {
     OUT out;
 
     PARTS:
-    // Xor(a,b) = Or(And(a, Not(b)), And(Not(a), b))
+    // Xor = (a AND !b) OR (!a AND b)
     Not(in=a, out=tmp1);
     Not(in=b, out=tmp2);
     And(a=a, b=tmp2, out=tmp3);