Incorrect link in README.md and Learn.co Portal

[brianfishman]

The link "0, 1" (line 67 of README.md) does not work, and probably isn't intended to be a link.

Based on the raw file, I believe that it is supposed to be viewed as this: [0, 1] (0 inclusive, 1 non-inclusive)
Instead it creates an invalid link due to Markdown being supported.

As a result, when clicked:

• From the Learn.co portal:
  • When logged in, it returns you to your current page with a red error message saying "You do not have access to this lesson"
  • When logged out, it brings you to a 404 error page
• From github:
  • It opens up a 404 error page