Scope: Expand Preparing your Environment section to be more generic and not focus solely on Red Hat requirements.

Per Slack conversation, update as follows: 

I think we might be better of updating the guide to be more generic. E.g. the guide should say install a Java 17 or Java 21 compatible JVM, such as Temurin OpenJDK (link to Adoptium), IBM Semeru (link to Semeru download on ibm.com), or Red Hat OpenJDK (link to Red Hat OpenJDK download).

SME: olubyans@redhat.com / rhn-sa-tqvarnst