Update SECURITY.md

[niStee]

What does this PR do

Standards checklist

• The PR title is descriptive.
• I have read CONTRIBUTING.md
• Optional: I have tested the code myself

For new steps

• Optional: Topgrade skips this step where needed
• Optional: The --dry-run option works with this step
• Optional: The --yes option works with this step if it is supported by
  the underlying command

If you developed a feature or a bug fix for someone else and you do not have the
means to test it, please tag this person here.

[SteveLauC]

Thanks! Let me add this to the release procedure so that I won't forget it in the future. 😵‍💫