documentation reference to require cson and CSON? (minor)

[robjens]

The introduction mentions require("cson") however, later in the API part of the README.md file, a chain is shown using require('CSON') the latter of which, can't be found. I know it is conventional (by some) to write CSON for the variable name so I think this is a honest mistake. It probably should be cson (all lower case) in the API part of the readme example code...