Fix StackOverflow formatting typo in README.md (backport #847)

[mergify]

Summary

Fix StackOverflow formatting typo in README.md.

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This is an automatic backport of pull request #847 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 6a30bdf has failed:

On branch mergify/bp/stable/0.7/pr-847
Your branch is up to date with 'origin/stable/0.7'.

You are currently cherry-picking commit 6a30bdf.
  (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 <file>..." to mark resolution)
	both modified:   README.md
	both modified:   constraints.txt

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

The base branch was changed.

[woodsp-ibm]

This was going to the wrong branch (stable/0/7) as the post release PR has not been merged which changes mergify stable target. And it has used the stable 0.7 as the code so while I tried changing the target to stable/0.8 it has far far too many conflicts. I think the easiest is just to close this and do a PR direct to stable/0.8 as its just a small amount of change

[edoaltamura]

Oh no! I agree, let me open a different PR now. Do I understand correctly that once #844 is in mergify should indeed select the stable0.8 branch?

[woodsp-ibm]

Do I understand correctly that once....

Yes, the config change in that PR for mergify will have it use the new stable branch once that is merged,

[edoaltamura]

Great! It should work from now on. I have created a new PR directly to the stable branch for the moment.
Also, mergify created this branch mergify/bp/stable/0.7/pr-847, which I assume can be deleted now?