RFR: Update README.md to be used as Release Notes for Leyden EA 2

[Vladimir Kozlov]

On Wed, 27 Aug 2025 03:22:29 GMT, Ioi Lam <iklam at openjdk.org> wrote:

> In Leyden EA 1, we used a special version of README.md as the release nodes:
> 
> https://jdk.java.net/leyden/ -> [Release Notes](https://github.com/openjdk/leyden/blob/leyden-ea1-release-notes/README.md)
> 
> As we are releasing Leyden EA 2, we will use the same process for the release notes.
> 
> - The README.md is taken from the [GIT version of Leyden EA 2 candidate](https://github.com/openjdk/leyden/commit/ffacb36e564b24e335b11fe5be8e574dffac2055) (as of today).
> - Removed information about building and benchmarks
> - Removed mentions of AOT features that have already been integrated into the mainline.
> - Updated the terminology from "CDS" to "AOT"
> 
> A rendered version of this document can be found here:
> - https://github.com/iklam/leyden/blob/leyden-ea2-release-notes/README.md
> 
> (I will merge some of the above changes back to leyden/premain branch after this PR is integrated).

Add to limitations section that AOT code will be only used if run on machine with the same type of CPU as used for training. Otherwise AOT code will be ignored.

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PR Comment: https://git.openjdk.org/leyden/pull/92#issuecomment-3226640756