add --minify option to cli & document options for minifying the bundle when using the js api

[sethvincent]

Example:

"scripts": {
    "bundle:min": "browserify index.js -t minidocs/transform -g unassertify -g yo-yoify -g es2020 -g uglifyify -t envify -p bundle-collapser/plugin > bundle.min.js",
    "bundle": "browserify index.js -o bundle.js -t minidocs/transform",
    "start": "budo index.js:bundle.js -l -P -- -t minidocs/transform -g unassertify -g yo-yoify -g es2020 -g uglifyify -t envify -p bundle-collapser/plugin"
  },