Add SECURITY.md policy, code scan policy, dependabot etc

[Zealot88]

Hi,
I'm new to Livepeer, and I've been looking at installing an orchestrator today. I'm security minded for any project that I'm involved in, especially for crypto services. Awesome work, by the way.

I forked the project to assess where the project is with security, so I applied the GitHub security tools, code scanner (not finished yet still running), dependabot, and secrets detection. I basically added all the security tools for scanning the project. For now I can only say that there are 4 findings:

I would recommend you add a security policy to the project to automate the inclusion of the fixes proposed, from dependabot in this case, simply to improve the security of the project.

Cheers.

Edit: I see that you have dependabot configured... doh :D