Remove uneccesary colon (#7238)

Only use a colon after a statement that is a complete sentence, like [Grammer Girl says](http://www.quickanddirtytips.com/education/grammar/colons).
(cherry picked from commit 4730971)

Author: Zac Smith

docs/docs/08.1-more-about-refs.md

@@ -5,7 +5,7 @@ permalink: more-about-refs.html
 prev: working-with-the-browser.html
 next: tooling-integration.html
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-After building your component, you may find yourself wanting to "reach out" and invoke methods on component instances returned from `render()`. In most cases, this should be unnecessary because the reactive data flow always ensures that the most recent props are sent to each child that is output from `render()`. However, there are a few cases where it still might be necessary or beneficial, so React provides an escape hatch known as `refs`. These `refs` (references) are especially useful when you need to: find the DOM markup rendered by a component (for instance, to position it absolutely), use React components in a larger non-React application, or transition your existing codebase to React.
+After building your component, you may find yourself wanting to "reach out" and invoke methods on component instances returned from `render()`. In most cases, this should be unnecessary because the reactive data flow always ensures that the most recent props are sent to each child that is output from `render()`. However, there are a few cases where it still might be necessary or beneficial, so React provides an escape hatch known as `refs`. These `refs` (references) are especially useful when you need to find the DOM markup rendered by a component (for instance, to position it absolutely), use React components in a larger non-React application, or transition your existing codebase to React.
 
 Let's look at how to get a ref, and then dive into a complete example.