fix the docstring for scale_docs

Current version of `scale_docs` string strips the leading whitespace from the `get_scale_docs` function. This fixes the alignment so that 'linear' aligns with 'log', which is not currently happening in the below screenshot from the documentation page:

![screen shot 2013-08-19 at 15 52 36](https://f.cloud.github.com/assets/255672/989299/ade9e718-0911-11e3-88c6-f7b66a75af0f.png)