README: add notes about options and usage

Author: Adam Gruber

README.md

@@ -86,6 +86,50 @@ It will yield the following object:
 }
 ```
 
+## Right on! But I need options.
+
+Everybody loves options and we've got one:
+
+Option Name | Default | Description 
+:---------- | :------ | :----------
+`camelCase` | true    | Should SASS variable names be converted to camelCase
+
+### Options Usage
+
+#### Plugin Instance
+
+Currently there is no way to pass plugin options through sass-extract's render or extract api. However, you *can* pass a plugin instance directly inside the plugins array instead of a string. Here's how to do it:
+
+```js
+// Import the plugin factory directly
+import createSassExtractJsPlugin from 'sass-extract-js/lib/plugin';
+
+// Create a plugin instance, passing in your options
+const sassExtractJsPlugin = createSassExtractJsPlugin({ camelCase: false });
+
+// Call the `renderSync` function with the path to your Sass file
+// and pass the plugin instance in the plugins array
+const rendered = sassExtract.renderSync({
+  file: './path/to/vars.scss'
+}, {
+  plugins: [sassExtractJsPlugin]
+});
+
+```
+
+#### Using `transformVars` directly
+
+If, for some reason, you don't want to use this package as a sass-extract plugin, you can import the `transformVars` function directly and use it. This is the main function that gets called in sass-extract's plugin pipeline. It expects as its input an object with extracted SASS variables, as generated by sass-extract. The function also accepts an options object.
+
+```js
+// Import the transformVars method directly
+import transformVars from 'sass-extract-js/lib/transformVars';
+
+// Call the function, passing in your options
+const trasformed = transformVars(objectWithExtractedStyles, { camelCase: false });
+```
+
+
 ## Wait! What if I don't use styled-components?
 
 No problem! I made this so I could use the extracted JS object as a theme but it's not specific to [styled-components][styled-components]. It should work the same with [glamorous][glamorous] too. Really you can use this plugin for any scenario where you need to convert Sass vars to JS.
@@ -94,6 +138,10 @@ No problem! I made this so I could use the extracted JS object as a theme but it
 
 This project is open source. I've tried to make sure it works for a lot of use cases (read: mine) but if I missed yours, feel free to [open an issue][issues]. Better yet, [submit a PR][pr]! Seriously, any feedback and help is welcome.
 
+## License
+
+MIT
+
 [issues]: https://github.com/adamgruber/sass-extract-js/issues
 [pr]: https://github.com/adamgruber/sass-extract-js/pulls
 [styled-components]: https://www.styled-components.com/