Fix README.md on merge into master from PR example

[nmichlo]

Fix example based on discussion in #215

Summary of changes

Do any of the followings changes break current behaviour or configuration?

• NO

How changes have been tested

• in my own private repos to resolve the issues discussed in: squash and merge tags original branch not new target #215
  • don't tag old branch if PR is just closed (cancelled), instead of closed by merging
  • don't tag the original branch, rather tag the commit created by the merge (fixes squash and rebase PRs)

List any unknowns

• N/A

[sbe-arg]

Can you sort the conflicts so we get this merged?

[nmichlo]

@sbe-arg, I've resolved the conflict thanks!