Fix http link to https link for security, modify many link http to https in the project. Signed-off-by: Nguyen Hai Truong <truongnh@vn.fujitsu.com>
The kubernetes contributor cheat-sheet has been made into a directory. The PR discussing this change can be found [here](https://github.com/kubernetes/community/pull/3213). I have adjusted the link to point to the correct documentation