Add inline comments to modules-and-ports tb.sv

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: thomasahle

src/lessons/sv/modules-and-ports/tb.sv

@@ -1,8 +1,11 @@
 module tb;
-  logic [7:0] a, b, sum;
+  logic [7:0] a, b, sum;  // stimulus signals
+
+  // Instantiate the design under test, connecting ports by name
   adder dut(.a(a), .b(b), .sum(sum));
+
   initial begin
-    a = 8'd10; b = 8'd32;
-    #1 $display("sum = %0d", sum);
+    a = 8'd10; b = 8'd32;       // apply inputs
+    #1 $display("sum = %0d", sum); // wait 1 time unit, then print result
   end
 endmodule