kleidiai: Update KleidiAI Documentation

[JonathanC-ARM]

Overview

This PR updates KleidiAI documentation to be in line with changes from PR1 #26076 and PR2 #26077

Additional information

This pr is intended to be 3/3 in a series of pr's to improve the KleidiAI with its cpu feature detection, build system and documentation.

PR 1 - #26076
PR 2 - #26077

Requirements

• I have read and agree with the contributing guidelines - YES
• AI usage disclosure: YES - AI was used to help understand llama.cpp

[ggml-gh-bot]

Hi @JonathanC-ARM, thanks for your contribution!

Per our contribution guidelines, the automated PR checker found the following issue(s) that need your attention:

• Multiple open PRs from a new contributor: We limit new contributors (those without a previously merged PR) to 1 open PR at a time. You currently have 3 open PRs.

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Please note that maintainers reserve the right to make final decisions on PRs. If you believe there is a mistake, please comment below.

[JonathanC-ARM]

Hi @JonathanC-ARM, thanks for your contribution!

Per our contribution guidelines, the automated PR checker found the following issue(s) that need your attention:

* **Multiple open PRs from a new contributor**: We limit new contributors (those without a previously merged PR) to **1 open PR at a time**. You currently have 3 open PRs.

Please note that maintainers reserve the right to make final decisions on PRs. If you believe there is a mistake, please comment below.

Similar to the other pr this assesment is correct, however the approach here from my part was to give context to a series of work. This pr is draft and is not required to be acted upon and will only be updated and pursued if and when PR 1 and 2 in this series is accepted.