RFC 167: Update documentation to reflect changes on license tags

Created by: unknwon

Update our handbook for sales about "what are the rules to issue new licenses". https://github.com/sourcegraph/about/pull/1747
Update description on generate license UI. https://github.com/sourcegraph/sourcegraph/pull/14614

Screen Shot 2020-10-12 at 4 53 22 PM

Should do it after https://github.com/sourcegraph/sourcegraph/issues/14021.

Part of RFC 167.