[4.3.0] Add HTTPS transport change to Mutual SSL docs

[tharikaGitHub]

Purpose

This PR adds recommendation for using HTTPS with Mutual SSL. Fixes #8329

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}