doc: add an LTS-LTS changelog

[HarshithaKP]

document notable changes between v10 to v12 for easy consumption
fixes: #26891

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines

[jasnell]

Hmm... if we're going to do this we should do it consistently for all majors. @nodejs/releasers thoughts?

[jasnell]

In general, I appreciate the intention of this, but there are a number of issues:

1. Every major release changelog already contains a complete listing of all semver-major changes since the last major and the minors are already included. What might be better than a document like this is a blog post that is automatically assembled with a complete listing of the semver-major and minor changes.

2. Given that there are no links to any of the changes, it's really not easy to track the changes back to the relevant context. That is, the existing changelog provides a lot more detail.

I do think it would be great to iterate on our release notes, however, and I know that @BridgeAR has had some thoughts on this.

[richardlau]

For the specific Node.js 10->12 notable changes, @bnb put together https://nodejs.org/en/blog/uncategorized/10-lts-to-12-lts/ (nodejs/nodejs.org#2701).

[HarshithaKP]

I was trying to help here after reviewing #26891 that had several thumbs ups and no objections.
w.r.t to linked blog, I did not see that earlier, but these are the key changes:

• I don’t have a section most notable changes
• I kept all notable changes, segregated based on subsystems
• I removed the full list of commits
  the aim is to achieve easy discovery and easy consumption.

[Trott]

@Ginden Would the document added in this PR be useful for you? I'm thinking probably not because it doesn't link to descriptions of the changes etc., but I may be making incorrect assumptions.

[HarshithaKP]

Closing this, as @Ginden (original issue raiser) is happy with the original documentation.