content: modify comment in pipelines article

Add 'the' in front of 'output' to clear up any possible confusion with the
variable 'output' declared in the previous function.

Change-Id: I6e85a068d29f338d51d3c9c5bd636b850dd308ca
Reviewed-on: https://go-review.googlesource.com/114821
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
diff --git a/content/pipelines/sqleak.go b/content/pipelines/sqleak.go
index 4333205..47d99a6 100644
--- a/content/pipelines/sqleak.go
+++ b/content/pipelines/sqleak.go
@@ -68,7 +68,7 @@
 	c1 := sq(in)
 	c2 := sq(in)
 
-	// Consume the first value from output.
+	// Consume the first value from the output.
 	out := merge(c1, c2)
 	fmt.Println(<-out) // 4 or 9
 	return