RFR: 1102: Document minimum required JDK version 16 for Skara [v2]

[Iris Clark]

On Wed, 7 Jul 2021 20:13:23 GMT, Erik Joelsson <erikj at openjdk.org> wrote:

>> Change documentation to reflect that Skara now requires JDK 16 to build.
>
> Erik Joelsson has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Update example

README.md line 49:

> 47: ## Building
> 48: 
> 49: [JDK 16](http://jdk.java.net/16/) or later and [Gradle](https://gradle.org/)

How often is the minimum JDK version for Skara updated?  If it's always the last GA'd version of the JDK, perhaps that sort of phrasing should be used instead?

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PR: https://git.openjdk.java.net/skara/pull/1195