doc: fix typo

Change-Id: I640dbeb5fe2b2f7eb46e4c46790bde9f209c74bf
Reviewed-on: https://go-review.googlesource.com/34919
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
diff --git a/build.go b/build.go
index cd75355..7d94196 100644
--- a/build.go
+++ b/build.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Package build contains constants for the Go continous build system.
+// Package build contains constants for the Go continuous build system.
 package build
 
 import (