docs: Add a few well known interconnects to the Hardware Metadata File page

[amacleod]

Fixes #2562

Added two sentences to list the same set of interconnects that have pinouts shown in the New Keyboard Shield guide and point readers at the interconnects directory in source for more.

[nmunnich]

Thanks for the PR! The interconnects can be found in multiple locations, having hardware metadata be another one seems like a good addition to me. I don't think plaintext is the way to go, though; I'd say we want something along the lines of hardware list where it uses some typescript to pull the information from the metadata directly.

[caksoylar]

For a more limited dynamic use of metadata, you can also check out the shield overlays section which gets the interconnect metadata: https://github.com/zmkfirmware/zmk/blob/main/docs/docs/development/hardware-integration/new-shield.mdx?plain=1#L269

This is essentially reading from these files https://github.com/zmkfirmware/zmk/tree/main/app/boards/interconnects and you'd only need to get the id and name for enumerating them in this page.

[github-actions[bot]]

This PR has been automatically marked as stale because it has not had activity in 10 months. It will be closed in 14 days if no further activity occurs. Feel free to give a status update or re-open when it has been rebased and is ready for review (again). Thanks!

[github-actions[bot]]

This PR was closed because it had no activity for over 10 months. Feel free to give a status update or re-open when it has been rebased and is ready for review (again).