Document how to increase ulimits for use with hyperspec

When using hyperspec + capybara + chrome with browser + binding.pry you can get errors if you try to run a capybara command in pry that fails.

For example `find('.class-that-does-not-exist')` in a pry breakpoint will fail with a too many open connections message.

Its easy enough however to change the ulimit so this does not happen, and this should be documented so people don't get frustrated by this.

This is a good write up on how to do it: https://wilsonmar.github.io/maximum-limits/