Add global attributes to asciidoc

[gdams]

We should use global attributes to set variables that are used on multiple pages (e.g latest Temurin 8 version) this will also make it easier to update the variables when we do releases

[xavierfacq]

Do you have an exemple of variable that could be moved as a global attribute?

[xavierfacq]

NOTE: the idea was to use variables in asciidoc docs pages.

E.g the Linux installation page (https://github.com/adoptium/adoptium.net/blob/main/content/asciidoc-pages/installation/linux/index.adoc)

We would normally update this from temurin-17-jdk to temurin-21-jdk but I’d rather make use of the latestLTS variable that we set in graphql and inject it into the document