Add NPM package RE and fix README.md generation

[zanerock]

Overview

Let's get an RE for a NPM package name.

While we're at it, I notice the README.md is not regenerating. It needs to take note of changes in the JS files.

Deliverables

• [x] define the new RE
• [x] fix README.mk recipe and regenerate docs

[zanerock]

Work for this issue will begin begin on branch work-liquid-labs/regex-repo/21.