Add SECURITY.md

[sdushantha]

The SECURITY.md file has become a standard for open source projects. This file can contain something very simple like an e-mail address with some basic steps to follow in order report a vulnerability. Ollama's SECURITY.md can be used as an inspiration: https://github.com/ollama/ollama/security

[ognevsd]

Here is also some info from OSSF scorecard: https://github.com/ossf/scorecard/blob/main/docs/checks.md#security-policy