RFR: Section on backporting [v6]

[Christoph Langer]

On Thu, 25 Nov 2021 18:17:46 GMT, Jesper Wilhelmsson <jwilhelm at openjdk.org> wrote:

>> Guidance on backporting.
>> Also moved "Backing out a change" to the testing section where I believe it fits better. This section is unchanged.
>
> Jesper Wilhelmsson has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Update src/index.md
>   
>   Co-authored-by: Andrew Haley <aph-open at littlepinkcloud.com>

Looks good.

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Marked as reviewed by clanger (no project role).

PR: https://git.openjdk.java.net/guide/pull/66