Add an explanation of this repository vs. OpenCVDB

[christophetd]

As discussed in: https://cloudsecurityforum.slack.com/archives/CNJKBFXMH/p1653571696703509

It would be great to clarify what's the scope and mission of this repository in comparison to https://github.com/SummitRoute/csp_security_mistakes (now https://github.com/wiz-sec/open-cvdb).

Scott's repository was created in late 2021 and most in the community are familiar with it. I'm afraid that by having two similar repositories, it will get very confusing for everyone.

You currently link to OpenCVDB at the very bottom, but we should probably aim for an explanation at the top of the readme, especially what's the difference and how the two relate together.