chore: add Makefile; REUSE v3.3 compliance, update README

[synackd]

Pull Request Template

Thank you for your contribution! Please ensure the following before submitting:

Checklist

• My code follows the style guidelines of this project
• I have added/updated comments where needed
• I have added tests that prove my fix is effective or my feature works
• I have run make test (or equivalent) locally and all tests pass
• DCO Sign-off: All commits are signed off (git commit -s) with my real name and email
• REUSE Compliance:
  • Each new/modified source file has SPDX copyright and license headers
  • Any non-commentable files include a <filename>.license sidecar
  • All referenced licenses are present in the LICENSES/ directory

Description

Add a Makefile to:

• Automate binary and container builds
• Make Goreleaser builds easier (make goreleaser-* targets set environment variables automatically)
• Add make test to comply with the "I have run make test" in the PR template
• Add other helpful targets such as lint

Add REUSE v3.3 compliance to conform to the PR template.

Update the documentation in accordance with the above, as well as updating old links and instructions, etc.

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation update

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For more info, see Contributing Guidelines.

[davidallendj]

LGTM! I made sure that the make command worked with all of the rules and the testing section works too.