Fix "Install standalone Elastic Agents" page to include macOS on ARM commands

[kilfoyle]

On the Install standalone Elastic Agents page:

1. We show the command for macOS on Intel but not for ARM. We instead just have a note saying that ARM is also available. We should have two widgets for macOS. A user had pointed this out in a discussion thread.

2. We refer to "AMD" but this should say "Intel".

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Note: Here's the PR that updated that section of the page: #510

[kilfoyle]

Fixed by elastic/docs-content#1310 and elastic/docs-content#1313.