add whitespace example

docs/recipes/sha-256.md

@@ -104,8 +104,8 @@ Using SHA hash code to confirm the element changes is a bad practice in opinion.
     .getElementById('load')
     .addEventListener('click', () => {
       document.getElementById('output').innerHTML = `
-      <div>Error loading...</div>
-    `
+        <div>Error loading...</div>
+      `
     })
 </script>
 ```
@@ -150,6 +150,15 @@ cy.get('#output')
 
 The page does change and the element's HTML has a new SHA, but is this a good test? Absolutely not. The page shows an error element, not successfully loaded data. The test should confirm one successful output, not try to assertion that a million different possible _other_ outputs do not appear.
 
+SHA code changes even when the only changes are invisible to the user, like whitespace around elements.
+
+```js
+expect(
+  digestMessage('<div>Hello</div>'),
+  'extra space at the end',
+).to.not.equal(digestMessage('<div>Hello</div> '))
+```
+
 **Note:** there is also a subtle timing bug in the above test, something that affects every test framework that relies only on promises or `async/await` syntax to execute its commands.
 
 <!-- fiddle-end -->