Add security.txt file

[kevinweaver]

Issue

The Security team suggested we follow suit with a recent initiative by Metamask to add the https://securitytxt.org/ .well-known file to the website. The intention is to point outside contributors to our bug bounty.

Steps to Reproduce

I should be able to navigate to: https://trufflesuite.com/.well-known/security.txt

Expected Behavior

I should see a link to https://hackerone.com/consensys for bug bounty submissions.

This could instead direct to a full page if we feel that it's worth it. For context, here is the staging version of metamask.io’s new bounty page: https://metamask.consensys.net/security/)

Environment

• Operating System:
• Ethereum client:
• Truffle version (truffle version):
• node version (node --version):
• npm version (npm --version):

[fainashalts]

Note to whoever works on this issue: We discussed this in ticket processing, and we've decided we should just create the security.txt file rather than a full page for it.