Improve build instructions for external developers

[d108]

First time contributor checklist

• [x] I have read the README and CONTRIBUTING documents
• [x] I have signed the Contributor Licence Agreement

Contributor checklist

• [x] My commits are rebased on the latest main branch

• [x] My commits are in nice logical chunks

• [x] My contribution is fully baked and is ready to be merged as is

• [x] I have tested my contribution on these devices:

• Built with Xcode 14.2

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Description

Updating BUILDING after testing a successful build procedure to help external developers become more efficient in trying the project.

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This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

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This issue has been closed due to inactivity.