Tiny follow up to #12983 (backport #12999)

[mergify]

Summary

Tiny follow up on #12983 fixing a typos & updating releasenotes.

Details and comments

Since MUMBAI_CMAP is only internally available, I suggested a change to a full example in the reno 🙂

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This is an automatic backport of pull request #12999 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of b90c7a7 has failed:

On branch mergify/bp/stable/1.2/pr-12999
Your branch is up to date with 'origin/stable/1.2'.

You are currently cherry-picking commit b90c7a706.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
	both modified:   qiskit/transpiler/passes/routing/stochastic_swap.py
	deleted by us:   releasenotes/notes/deprecate-StochasticSwap-451f46b273602b7b.yaml

no changes added to commit (use "git add" and/or "git commit -a")

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[qiskit-bot]

Thank you for opening a new pull request.

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One or more of the following people are relevant to this code:

• @Qiskit/terra-core

[ElePT]

Accidentally triggered the backport for this PR that didn't need it.