scancode-toolkit doc on license scoring

[steven-esser]

We need to have a somewhat detailed entry/doc page on license scoring:

• How its calculated
• What different scores mean
• How to interpret, etc

[mjherzog]

This Issue should be move to nexb/scancode-toolkit

[AyanSinhaMahapatra]

@mjherzog It's now tracked here. This Issue can be closed. Also, as I was working on license detection recently, I now understand and will update the docs soon.

[mjherzog]

Closed in favor of aboutcode-org/scancode-toolkit#1813