Change anynymous functions to named functions on examples in the README.md file (#6255)
Change anynymous functions to named functions on examples in the README.md file (#6255)

* convert export default anonymous functions into named functions

* change examples to function declaration and split export in classes

* change NextHead name to Head and rename component

zeit/next.js,zeit/next.js,azukaru/next.js,flybayer/next.js,JeromeFitz/next.js,azukaru/next.js,azukaru/next.js,JeromeFitz/next.js,azukaru/next.js,flybayer/next.js,BlancheXu/test,JeromeFitz/next.js,BlancheXu/test,JeromeFitz/next.js,BlancheXu/test,flybayer/next.js,zeit/next.js,flybayer/next.js