Add "since" badge or text, similar to ibm.com documentation

[bmarwell]

Subject:

Since Badge.

Background:

Some features are relatively new, some options started appearing with a specific version.
It would be helpful to see when (first release and/or release date) an option, feature or an enhancement was added.

The (almost exactly same) documentation on ibm.com does exactly this.

Other things to think about

• Minimum OpenJ9 version
• Java Language Level (if the feature, CLI option etc. does not apply to all current and future versions)
• Deprecated ([for removal]) (since $version) // deprecated for removal in $version
• Removed in (version)

Suggestion:

Add a since badge.

E.g.

• when did https://eclipse.dev/openj9/docs/xxadaptivegcthreading/ arrive?
• Can I use it with my older (but maybe still supported) JVM?
• Is it available on all Java language levels?