📝 Add Security policy

SECURITY.md

@@ -0,0 +1,29 @@
+# Security Policy
+
+Security is very important for Typer and its community. 🔒
+
+Learn more about it below. 👇
+
+## Versions
+
+The latest versions of Typer are supported.
+
+You are encouraged to [write tests](https://typer.tiangolo.com/tutorial/testing/) for your application and update your Typer version frequently after ensuring that your tests are passing. This way you will benefit from the latest features, bug fixes, and **security fixes**.
+
+## Reporting a Vulnerability
+
+If you think you found a vulnerability, and even if you are not sure about it, please report it right away by sending an email to: security@tiangolo.com. Please try to be as explicit as possible, describing all the steps and example code to reproduce the security issue.
+
+I (the author, [@tiangolo](https://twitter.com/tiangolo)) will review it thoroughly and get back to you.
+
+## Public Discussions
+
+Please restrain from publicly discussing a potential security vulnerability. 🙊
+
+It's better to discuss privately and try to find a solution first, to limit the potential impact as much as possible.
+
+---
+
+Thanks for your help!
+
+The Typer community and I thank you for that. 🙇