[doc] Issue in "Prerequisites"

[joesusecom]

Prerequisites:

https://suse-edge.github.io/quickstart-eib.html#id-prerequisites-2

I've been testing exclusively on SLE Micro 6.0 (with the config in /opt/eib) for the last couple of weeks, and I think we can add it to the list of supported runtimes with confidence.

The problem with the current list is that none of those options is supported as part of the SUSE Edge Suite. :-)