ssh/testdata: correct typo

Change-Id: I93275a7aa048bab63bcf5dafe8582a0fcd7802ae
GitHub-Last-Rev: d56c40c905351af5d9555b2966ea793328655ee4
GitHub-Pull-Request: golang/crypto#60
Reviewed-on: https://go-review.googlesource.com/c/142077
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

ssh/testdata/keys.go

@@ -155,7 +155,7 @@ var SSHCertificates = map[string][]byte{
 	// Generated by the following commands:
 	//
 	// 1. Assumes "rsa" key above in file named "rsa", write out the public key to "rsa.pub":
-	//    ssh-keygen -y -f rsa > rsa.pu
+	//    ssh-keygen -y -f rsa > rsa.pub
 	//
 	// 2. Assumes "ca" key above in file named "ca", sign a cert for "rsa.pub":
 	//    ssh-keygen -s ca -h -n host.example.com -V +500w -I host.example.com-key rsa.pub