[DOC] Fix Handlebars `input` Helper Doc Rendering

Before
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![screen shot 2014-10-26 at 3 04 02 pm](https://cloud.githubusercontent.com/assets/3300/4784092/e1430f32-5d42-11e4-8bce-b492c90dc05b.png)

After
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![screen shot 2014-10-26 at 3 02 34 pm](https://cloud.githubusercontent.com/assets/3300/4784091/d142c334-5d42-11e4-9072-9c3e4a3936d5.png)