Expand automatic pre-rendering docs (#7702)
Expand automatic pre-rendering docs (#7702)

* Expand automatic pre-rendering docs

* Apply suggestions from code review

Co-Authored-By: Luis Fernando Alvarez D. <faea5242a00c52da62a0f00df168c199b7ab748d@zeit.co>

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