clientcredentials: fix comment for Client struct to match godoc style

Godoc comments should start with the name of the thing they are describing.

Change-Id: Ic248aa8f549b22c716bf967c7574452085ea8c48
Reviewed-on: https://go-review.googlesource.com/36945
Reviewed-by: Chris Broadfoot <cbro@golang.org>
diff --git a/clientcredentials/clientcredentials.go b/clientcredentials/clientcredentials.go
index 1b64956..26bc838 100644
--- a/clientcredentials/clientcredentials.go
+++ b/clientcredentials/clientcredentials.go
@@ -23,7 +23,7 @@
 	"golang.org/x/oauth2/internal"
 )
 
-// Client Credentials Config describes a 2-legged OAuth2 flow, with both the
+// Config describes a 2-legged OAuth2 flow, with both the
 // client application information and the server's endpoint URLs.
 type Config struct {
 	// ClientID is the application's ID.