Add doc comments to the minify file util. [ci skip]

lib/common/minify.js

@@ -8,6 +8,19 @@ var uglifyOptions = require('./uglify.options');
 
 /*----------------------------------------------------------------------------*/
 
+/**
+ * Asynchronously minifies the file at `srcPath`, writes it to `destPath`, and
+ * invokes `callback` upon completion. The callback is invoked with one argument:
+ * (error).
+ *
+ * If unspecified, `destPath` is `srcPath` with an extension of `.min.js`. For
+ * example, a `srcPath` of `path/to/foo.js` would have a `destPath` of `path/to/foo.min.js`.
+ *
+ * @param {string} srcPath The path of the file to minify.
+ * @param {string} [destPath] The path to write the file to.
+ * @param {Function} callback The function invoked upon completion.
+ * @param {Object} [option] The UglifyJS options object.
+ */
 function minify(srcPath, destPath, callback, options) {
   if (_.isFunction(destPath)) {
     if (_.isObject(callback)) {

lib/common/uglify.options.js

@@ -1,5 +1,11 @@
 'use strict';
 
+/**
+ * The UglifyJS options object for
+ * [compress](https://github.com/mishoo/UglifyJS2#compressor-options),
+ * [mangle](https://github.com/mishoo/UglifyJS2#mangler-options), and
+ * [output](https://github.com/mishoo/UglifyJS2#beautifier-options) options.
+ */
 module.exports = {
   'compress': {
     'pure_getters': true,