ssh: fix typo in unexported comment

Thanks to Anisse Astier (@anisse) for noticing.

Change-Id: I1c282b2bb54601cf5649e194eafd5344c70331ca
Reviewed-on: https://go-review.googlesource.com/38916
Reviewed-by: dnv aps Sn <sndnvaps@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

ssh/common.go

@@ -40,7 +40,7 @@ var supportedKexAlgos = []string{
 	kexAlgoDH14SHA1, kexAlgoDH1SHA1,
 }
 
-// supportedKexAlgos specifies the supported host-key algorithms (i.e. methods
+// supportedHostKeyAlgos specifies the supported host-key algorithms (i.e. methods
 // of authenticating servers) in preference order.
 var supportedHostKeyAlgos = []string{
 	CertAlgoRSAv01, CertAlgoDSAv01, CertAlgoECDSA256v01,