Remove "Caller's Approach" section as redundant

[DScheglov]

The "Caller's Approach" section presents "Caller vs. Callee" as a choice, but the function returning Result can throw, so the approaches could coexist, making the distinction an artificial binary that ignores the technical reality of dual-channel error propagation.

The proposal is a syntax shortcut, not an architectural shift. It doesn't change how errors travel.

So. the section adds philosophical bloat to a purely ergonomic feature.