Update the Getting Started Guide to link to the Installation Guide

https://docs.wildfly.org/23/Getting_Started_Guide.html describes the unzip installation method. That's fine but it should be redrafted to note there are different options, link to https://docs.wildfly.org/23/Installation_Guide.html for more info, and then present its current brief details of downloading and unzipping as a quick description of the most common option. IOW don't force people to go to the Installation Guide to learn how to download/unzip, but make sure the options are known.