📖 proposal: add support for defining trunk subports

[bnallapeta]

What this PR does / why we need it: Proposal doc for #2861

/hold

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[bnallapeta]

/cc @lentzi90

[bnallapeta]

@lentzi90 do you have some time to take a look at this?

[winiciusallan]

Sorry for the delay! I don't have any immediate concerns. It looks like a useful feature. However, I think we should coordinate this with ORC so we don't end up making things unnecessarily painful later. There is already a Port resource in ORC, but I don't think it has Trunk support yet.

Hi @lentzi90! ORC already has a work still in progress to add a new Trunk controller on this PR. Since it is still in progress, I believe it can be aligned with CAPO interests.

(sorry for meddling)