Add eslint-plugin-emotion to docs (#636)

<!-- What changes are being made? (What feature/bug is being fixed here?) -->
**What**: Missing eslint plugin docs

<!-- Why are these changes necessary? -->
**Why**: To expose the plugin!

<!-- How were these changes implemented? -->
**How**: Using github edit function (I didn't test, I expect the live preview to show if it works) EDIT: it works :)

<!-- Have you done all of these things?  -->
**Checklist**:
<!-- add "N/A" to the end of each line that's irrelevant to your changes -->
<!-- to check an item, place an "x" in the box like so: "- [x] Documentation" -->
- [X] Documentation
- [ ] Tests
- [X] Code complete

<!-- feel free to add additional comments -->

![image](https://user-images.githubusercontent.com/368155/39139254-b3aaa928-4721-11e8-9bd2-6afbb015b34c.png)

docs/docs.yaml

@@ -36,10 +36,11 @@
     - emotion
     - react-emotion
     - babel-plugin-emotion
+    - eslint-plugin-emotion
     - emotion-server
     - emotion-theming
     - jest-emotion
     - create-emotion
     - create-emotion-styled
     - create-emotion-server
-    - preact-emotion
+    - preact-emotion