Docs: clarify that versioningStrategy 0 uses the workflow run number (#2220)

## Summary

Fixes #2155

The ersioningStrategy setting 0 documentation stated that **Build** uses
the un_number "for the CI/CD workflow". In practice, GITHUB_RUN_NUMBER
resolves to the run_number of the **currently executing workflow** --
which is the CI/CD workflow when CI/CD triggers the build, but is the
Test Next Major, Test Next Minor, or other workflow's own run_number
when those workflows trigger a build instead.

This causes confusion when users configure ersioningStrategy: 0 and
observe that the build number increments using a different counter than
expected when non-CI/CD workflows trigger the build.

## Root Cause

The ReadSettings action resolves \ directly, which is always the current
workflow's run_number. The documentation used "CI/CD workflow" as a
specific reference when it should say "current workflow run".

## Changes

- Scenarios/settings.md: Updated strategy 0 description from "for the
CI/CD workflow" to "of the current workflow run" and added a note
clarifying the cross-workflow behavior.
- Scenarios/settings.md: Updated unNumberOffset description from "the
CI/CD workflow uses" to "the current workflow run uses" for consistency.

## How to Test

Documentation change only -- no code is modified. Verify by reading the
updated ersioningStrategy section in Scenarios/settings.md and
confirming it accurately describes the behavior in
Actions/ReadSettings/ReadSettings.ps1 where \.appBuild =
\.runNumberOffset + [Int32](\).

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Co-authored-by: Maria Zhelezova <43066499+mazhelez@users.noreply.github.com>