RFR: Section about the release process [v4]

[Iris Clark]

On Thu, 12 Aug 2021 20:21:02 GMT, Jesper Wilhelmsson <jwilhelm at openjdk.org> wrote:

>> Answering some common questions around the release process.
>
> Jesper Wilhelmsson has updated the pull request incrementally with one additional commit since the last revision:
> 
>   More on backing out a change

Marked as reviewed by iris (Reviewer).

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PR: https://git.openjdk.java.net/guide/pull/62