[Doc-a-thon] Updating update-linux-agent

I reformatted the doc to use tabs. I also removed duplicated instructions for distros (like SLES 15 SP4 VS SLES 12 instructions, the same instructions work on both), and created instructions for a single distro and tested it on all distros (I even tested the instructions in RHEL 9, Oracle Linux 9, Ubuntu 22.04). I updated instructions and commands as well to use sudo and improved some of the content. I added as well a disclaimer for OL 6.x ELS support

Author: divargas-msft