Update http links to https

Change-Id: Ie2de4c427f234495c77b57ea0ce31cf41fa46ff1
GitHub-Last-Rev: e2d1d79ba359738ce6725a4627de674f9d5eb850
GitHub-Pull-Request: golang/gddo#568
Reviewed-on: https://go-review.googlesource.com/126575
Reviewed-by: Tuo Shan <shantuo@google.com>
1 file changed