errgroup: remove duplicated comment

Change-Id: I5cdcc5034ccd87b939a406693e97485553ab60fa
Reviewed-on: https://go-review.googlesource.com/c/sync/+/676715
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Alan Donovan <adonovan@google.com>
Auto-Submit: Alan Donovan <adonovan@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

Author: xieyuschen

errgroup/errgroup.go

@@ -76,10 +76,8 @@ func (g *Group) Wait() error {
 }
 
 // Go calls the given function in a new goroutine.
-// The first call to Go must happen before a Wait.
-// It blocks until the new goroutine can be added without the number of
-// active goroutines in the group exceeding the configured limit.
 //
+// The first call to Go must happen before a Wait.
 // It blocks until the new goroutine can be added without the number of
 // goroutines in the group exceeding the configured limit.
 //