Create SECURITY.md

[carpenter79]

I've created the SECURITY.md file considering the report vulnerability through security advisory, which is a new GitHub feature.

If you're interested in GitHub's feature, it must be activated for the repository:

Open the repo's settings Click on Code security & analysis Click "Enable" for "Private vulnerability reporting (Beta)" If you rather not enable it, there is also the possibility to receive the vulnerability report through an email. In this case just let me know what would be the email and I'll submit the change.

Besides that, feel free to edit or suggest any changes to this document. It is supposed to reflect the amount of effort the team can offer to handle vulnerabilities.