[docs] - add section on adding code locations for serverless

[prha]

Summary & Motivation

Add section on code locations in serverless, which are slightly different

How I Tested These Changes

Inspection

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[erinkcochran87]

@yuhan All good here - I took this over from Phil and addressed those in the commits I worked on (but haven't pushed yet). I'd been waiting on the image-in-tab issue to be resolved before merging, but I'll find another way to make this work so this isn't just hanging out here.