Add note to waitgroups example about errgroup

Fixes #308

examples/waitgroups/waitgroups.go

@@ -39,4 +39,9 @@ func main() {
 	// Block until the WaitGroup counter goes back to 0;
 	// all the workers notified they're done.
 	wg.Wait()
+
+	// Note that this approach has no straightforward way
+	// to propagate errors from workers. For more
+	// advanced use cases, consider using the
+	// [errgroup package](https://pkg.go.dev/golang.org/x/sync/errgroup).
 }

examples/waitgroups/waitgroups.hash

@@ -1,2 +1,2 @@
-fd77f5122e6df1669c0a2e0d2c4dfbd30631c21f
+b87ababcf7e1ce54107252c658840097bb6060a7
-7mWXl0yVe6I
+vXBl8zQpDYj

public/waitgroups

@@ -42,7 +42,7 @@ use a <em>wait group</em>.</p>
             
           </td>
           <td class="code leading">
-            <a href="http://play.golang.org/p/7mWXl0yVe6I"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
+            <a href="http://play.golang.org/p/vXBl8zQpDYj"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
           <pre class="chroma"><span class="kn">package</span> <span class="nx">main</span>
 </pre>
           </td>
@@ -165,10 +165,25 @@ counter for each.</p>
 all the workers notified they&rsquo;re done.</p>
 
           </td>
-          <td class="code">
+          <td class="code leading">
             
           <pre class="chroma">
     <span class="nx">wg</span><span class="p">.</span><span class="nf">Wait</span><span class="p">()</span>
+</pre>
+          </td>
+        </tr>
+        
+        <tr>
+          <td class="docs">
+            <p>Note that this approach has no straightforward way
+to propagate errors from workers. For more
+advanced use cases, consider using the
+<a href="https://pkg.go.dev/golang.org/x/sync/errgroup">errgroup package</a>.</p>
+
+          </td>
+          <td class="code">
+            
+          <pre class="chroma">
 <span class="p">}</span>
 </pre>
           </td>
@@ -223,7 +238,7 @@ is likely to be different for each invocation.</p>
     </div>
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-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"sync\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func worker(id int, wg *sync.WaitGroup) {\u000A');codeLines.push('    defer wg.Done()\u000A');codeLines.push('    fmt.Printf(\"Worker %d starting\\n\", id)\u000A');codeLines.push('    time.Sleep(time.Second)\u000A    fmt.Printf(\"Worker %d done\\n\", id)\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    var wg sync.WaitGroup\u000A');codeLines.push('    for i :\u003D 1; i \u003C\u003D 5; i++ {\u000A        wg.Add(1)\u000A        go worker(i, \u0026wg)\u000A    }\u000A');codeLines.push('    wg.Wait()\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"sync\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func worker(id int, wg *sync.WaitGroup) {\u000A');codeLines.push('    defer wg.Done()\u000A');codeLines.push('    fmt.Printf(\"Worker %d starting\\n\", id)\u000A');codeLines.push('    time.Sleep(time.Second)\u000A    fmt.Printf(\"Worker %d done\\n\", id)\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    var wg sync.WaitGroup\u000A');codeLines.push('    for i :\u003D 1; i \u003C\u003D 5; i++ {\u000A        wg.Add(1)\u000A        go worker(i, \u0026wg)\u000A    }\u000A');codeLines.push('    wg.Wait()\u000A');codeLines.push('}\u000A');codeLines.push('');codeLines.push('');
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