FEATURE: Add option to serve security.txt

[tillprochaska]

Is your feature request related to a problem? Please describe.
Security.txt is a common way to provide security contact information for web applications under a standard URL. This makes it easier for security researchers to report issues.

Describe the solution you'd like
Make it possible to configure a security contact address, link to public encryption key, link to security policy via environment variables and serve this information at /.well-known/security.txt.

Describe alternatives you've considered
-/-

Additional context

• https://en.wikipedia.org/wiki/Security.txt