Request: Various updates for installer pages

[adamfarley]

A few requests from @sxa as per the recent July 2025 retrospective:

Some "end user" installer notes:

• Linux install has the lines a little fragmented - perhaps we could have one box with all the commands that can be easily cut & pasted from?
• The initial apt commands to set up your machine before installing Temurin don't include gpg which is required and not present by default on the latest Ubuntu LTS
• We should have a note about STS vs LTS versions and update-alternatives (discussion) ref mailing list post. At the moment 24 (STS) will take priority over 21 (LTS) if both are installed.

Also while this is in my head:

• The main installer page tells you apt install temurin-21-jdk or similar but is it obvious to the end user that there are other instructions (later on) to set up the repos?
• We should maybe make reference to the new Fedora/EL10 temurin repository package in the docs.

[xavierfacq]

👋 Can you please, give the documentation URL your refer to?

[sxa]

It's https://adoptium.net/en-GB/installation and the "Read documentation" link at https://adoptium.net/en-GB/installation/linux

It's also always felt a bit strange that we have the two pages - first tells you about the apt/yum/dnf commands, but you can't use any of them until you set it up using the stuff in the "Read documentation" link 🤷🏻