docs: Correct links

Change-Id: I6dab30bfbca034ff0071f6d49cd0e0fd6f713494
diff --git a/docs/source/conf.py b/docs/source/conf.py
index 8bdfd9f..826e38a 100644
--- a/docs/source/conf.py
+++ b/docs/source/conf.py
@@ -280,4 +280,4 @@
 
 # aafig_default_options = dict(Fixed=True)
 
-redmine_project_url = "http://redmine.named-data.net/"
+redmine_project_url = "https://redmine.named-data.net/"