Specify default values of options in the README

[Hirse]

The Readme lists the available option of the parse function, but doesn't specify the default value for all of them.
From what I gathered from the source, it might make sense to update the example of the usage section to the following:

var espree = require("espree");

var ast = espree.parse(code, {

    // attach range information to each node
    range: false,

    // attach line/column location information to each node
    loc: false,

    // create a top-level comments array containing all comments
    comment: false,

    // attach comments to the closest relevant node as leadingComments and
    // trailingComments
    attachComment: false,

    // create a top-level tokens array containing all tokens
    tokens: false,

    // set to 3, 5 (default), 6, 7, or 8 to specify the version of ECMAScript syntax you want to use. 
    // You can also set to 2015 (same as 6), 2016 (same as 7), or 2017 (same as 8) to use the year-based naming.
    ecmaVersion: 5,

    // specify which type of script you're parsing (script or module, default is script)
    sourceType: "script",

    // specify additional language features
    ecmaFeatures: {

        // enable JSX parsing
        jsx: false,

        // enable return in global scope
        globalReturn: false,

        // enable implied strict mode (if ecmaVersion >= 5)
        impliedStrict: false,

        // allow experimental object rest/spread
        experimentalObjectRestSpread: false
    }
});

[kaicataldo]

Sorry for the delay in responding to this. I think this change makes sense - how could we make it clear these are the default values? And would you be willing to make a PR?

[Hirse]

Done: #342