RFR: 8347033: [mobile] add ios-specific build docs [v4]

[Magnus Ihse Bursie]

On Mon, 24 Feb 2025 09:16:35 GMT, Abhinay Agarwal <duke at openjdk.org> wrote:

>> Adds build instruction for iOS
>
> Abhinay Agarwal has updated the pull request incrementally with one additional commit since the last revision:
> 
>   move documentation to README.md

LGTM

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Marked as reviewed by ihse (Reviewer).

PR Review: https://git.openjdk.org/mobile/pull/34#pullrequestreview-2646177911