Fixed some typos on the documentation's index page.

The model layer

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Django provides an abstration layer (the "models") for structuring and

Django provides an abstraction layer (the "models") for structuring and

manipulating the data of your Web application. Learn more about it below:

* **Models:**

The view layer

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Django offers the concept of "views" to encapsulate the logic reponsible for

Django has the concept of "views" to encapsulate the logic responsible for

processing a user's request and for returning the response. Find all you need

to know about views via the links below: