Documentation: Document how to call Scorecard as a library.

[jeffmendoza]

• [ ] Enhance the go pkg documentation (ex: https://pkg.go.dev/github.com/ossf/scorecard/v5@v5.0.0/pkg/scorecard#Run) with description of how to run Scorecard with examples
• [ ] Add a section to the main README under Using Scorecard with a brief blurb about running as a library and linking to the go docs.
• [ ] (Possible / Later) Add a doc under the docs/ directory with a longer description of running Scorecard as a library

TBD: As we add more docs to scorecard.dev, where will this show up?

Source info: One example here: https://github.com/ossf/scorecard/issues/4254#issuecomment-2250953095 Design issue for new entrypoint: https://github.com/ossf/scorecard/issues/3717

[jeffmendoza]

I'm starting work on the first item.

[github-actions[bot]]

This issue has been marked stale because it has been open for 60 days with no activity.