docs: add asdf and mise installation method

[jylenhof]

Description

• Add basic documentation to install trivy tool using asdf and mise tool

Checklist

• I've read the guidelines for contributing to this repository.
• I've followed the conventions in the PR title.
• I've added tests that prove my fix is effective or that my feature works.
• I've updated the documentation with the relevant information (if needed).
• I've added usage information (if the PR introduces new options)
• I've included a "before" and "after" example to the description (if the PR is a user interface change).

[CLAassistant]

All committers have signed the CLA.

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
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[knqyf263]

Thanks for your contribution. We need your signature on our CLA.

[jylenhof]

It seems there's something wrong with the check on CLA...

You have agreed to the CLA for multiple repositories or organizations

Version: 2021-09-09

[knqyf263]

Are you using the same email address for CLA and commits?

[jylenhof]

Good catch, I use an alias for my email on github. Corrected

[knqyf263]

It's conflicting now

[knqyf263]

Thanks