rtt_timing: Added task D, as notet in reviews

examples/rtt_timing.rs

@@ -183,6 +183,18 @@ A/C = 4790151/40001 = 119,7507812 ~= 120
 // Open the file in you editor and search for the `timed_loop`.
 //
 // [Assembly for function `timed_loop` here]
+/*
+08000232 <timed_loop>:
+ 8000232:      	movw	r1, #4100   // Load 4100 into r1    (16-bit register)
+ 8000236:      	movw	r2, #10000  // Load 10000 into r2   (16-bit register)
+ 800023a:      	movt	r1, #57344  //
+ 800023e:      	ldr	r0, [r1]        // Load the content of E0001004 (probably the DWT register) into r0
+ 8000240:      	subs	r2, #1      // Decreases the loop counter with one
+ 8000242:      	nop                 // The instruction of the loop
+ 8000244:      	bne	#-8 <timed_loop+0xe>    // Branch not equal, two instructions back
+ 8000246:      	ldr	r1, [r1]        // Load the content of E0001004 into r1, no ide why
+ 8000248:      	bx	lr              // Branch back to link
+*/
 //
 // Locate the loop body, and verify that it makes sense
 // based on the information from the technical documentation: