fixed TypeScript definitions for follow functions - fixes issue #194

[glynnbird]

Overview

Fixes TypeScript defs for the follow functions. It's not just a plain EventEmitter that's returned.

Testing recommendations

tsc lib/nano.d.ts

GitHub issue number

194

Checklist

• [x] Code is written and works correctly;
• [x] Changes are covered by tests;
• [x] Documentation reflects the changes;