Update WaitGroup example

src/goroutine-exit.md

@@ -4,17 +4,13 @@ Given a goroutine spawned by the system,
 there must be a way to wait for the goroutine to exit.
 There are two popular ways to do this:
 
-- Use a `sync.WaitGroup`.
-  Do this if there are multiple goroutines that you want to wait for
+- Use a `sync.WaitGroup`, which does this with `Go` and `Wait`.
+  Do this if there are multiple goroutines that you want to wait for.
 
     ```go
     var wg sync.WaitGroup
     for i := 0; i < N; i++ {
-      wg.Add(1)
-      go func() {
-        defer wg.Done()
-        // ...
-      }()
+      wg.Go(...)
     }
 
     // To wait for all to finish:

style.md

@@ -2039,17 +2039,13 @@ Given a goroutine spawned by the system,
 there must be a way to wait for the goroutine to exit.
 There are two popular ways to do this:
 
-- Use a `sync.WaitGroup`.
-  Do this if there are multiple goroutines that you want to wait for
+- Use a `sync.WaitGroup`, which does this with `Go` and `Wait`.
+  Do this if there are multiple goroutines that you want to wait for.
 
   ```go
   var wg sync.WaitGroup
   for i := 0; i < N; i++ {
-    wg.Add(1)
-    go func() {
-      defer wg.Done()
-      // ...
-    }()
+    wg.Go(...)
   }
 
   // To wait for all to finish: