RFR: Added section for newcomers [v7]

[Joe Darcy]

On Fri, 20 Nov 2020 03:51:19 GMT, Jesper Wilhelmsson <jwilhelm at openjdk.org> wrote:

>> Added a section to the introduction to set the expectations for new developers in the OpenJDK.
>> 
>> I also moved the mail list section up since it's also relevant in this context and should (imho) be the first thing to learn about when thinking about joining the community.
>
> Jesper Wilhelmsson has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Less choking on coffee

src/index.md line 51:

> 49: Even though we strive to unify how things are done within the OpenJDK, different areas and projects in the OpenJDK may have slight variations in how they work. Some of these differences are highlighted throughout this guide, some aren't. If you're new to an area, make sure you understand local differences before you proceed. Ask your sponsor who should be your main point of contact through your first developer experience in the OpenJDK.
> 50: 
> 51: ## Why is my change rejected?

Another rationale for these concerns is the time-horizon of code in the JDK. Code in the JDK can be executed on all the devices/VMs for a decade or more after a change goes in.

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PR: https://git.openjdk.java.net/guide/pull/38