Update no-then.md

The 'improved code' after linting was unnecessarily complex introducing a named variable across multiple lines for no reason which made it look better to keep using `then`. A bit surprising.

Previous catch example was code which didn't differentiate between failing case (which is now a deliberate null) and undefined case (which is often the result of an error).

docs/rules/no-then.md

@@ -12,26 +12,39 @@ https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/asy
 
 👎 Examples of **incorrect** code for this rule:
 
+```js
+function countData(url) {
+  return downloadData(url).then(data => {
+    return data.length
+  })
+}
+```
+
 ```js
 function getProcessedData(url) {
   return downloadData(url).catch(e => {
     console.log('Error occurred!', e)
+    return null;
   })
 }
 ```
 
 👍 Examples of **correct** code for this rule:
 
+```js
+async function countProcessedData(url) {
+  const data = await downloadData(url);
+  return data.length
+```
+
 ```js
 async function getProcessedData(url) {
-  let v
   try {
-    v = await downloadData(url)
+    return await downloadData(url)
   } catch (e) {
-    console.log('Error occurred!', e)
-    return
+    console.log('Error occurred!', e);
+    return null;
   }
-  return v
 }
 ```