Clarify the conditions on the aliasing section

Author: JohnTitor

src/aliasing.md

@@ -31,16 +31,19 @@ fn compute(input: &u32, output: &mut u32) {
     if *input > 5 {
         *output *= 2;
     }
+    // remember that `output` will be `2` if `input > 10`
 }
 ```
 
 We would *like* to be able to optimize it to the following function:
 
 ```rust
 fn compute(input: &u32, output: &mut u32) {
-    let cached_input = *input; // keep *input in a register
+    let cached_input = *input; // keep `*input` in a register
     if cached_input > 10 {
-        *output = 2;  // x > 10 implies x > 5, so double and exit immediately
+        // x > 10 implies x > 5, so remove the first if condition,
+        // set it to `2`, and exit immediately
+        *output = 2;
     } else if cached_input > 5 {
         *output *= 2;
     }