doc: Mention of fiveg-n2 and fiveg-n4 requirers

[solmyrcan]

At the "Integration with the AMF N2 interface" section, we have:
"It is assumed that the fiveg-n2 requirer application is already deployed in the Juju model."
Do we have a how-to guide we can refer to which explains how the fiveg-n2 requirer application is deployed?

Similarly, at the "Integration with the UPF N4 interface" section, we have:
"It is assumed that the fiveg_n4 requirer application is already deployed in the Juju model."

for completeness and clarity, these two may need a link to relevant How-to, or the instruction could be embedded in the page.

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Document: how-to/deploy_sdcore_cups.md