Add forks to the README

[kaworu]

• #76
• https://github.com/kAworu/node-quirc/

[dignifiedquire]

Here is another one, started a port in rust using c2rust: https://github.com/dignifiedquire/quircs

[Jerakin]

Here is one for use in the Defold Game engine https://github.com/defold/extension-qrcode

[kaworu]

see also #104