Fix a couple typos

I feel this is what the author meant :)

docs/Tutorial.md

@@ -300,7 +300,7 @@ var {
 } = React;
 ```
 
-Now modify the render funtion so that once we have our data it renders a ListView of movies instead of a single movie.
+Now modify the render function so that once we have our data it renders a ListView of movies instead of a single movie.
 
 ```javascript
   render: function() {
@@ -318,9 +318,9 @@ Now modify the render funtion so that once we have our data it renders a ListVie
   },
 ```
 
-The `DataSource` is an interfacte that `ListView` is using to determine which rows have changed over the course of updates.
+The `DataSource` is an interface that `ListView` is using to determine which rows have changed over the course of updates.
 
-You'll notice we used `dataSource` from `this.state`. The next step is to add an empty `dataSource` to the object returned by `getInitialState`. Also, now that we're storing the data in `dataSource`, we should not longer use `this.state.movies` to avoid storing data twice. We can use boolean property of the state (`this.state.loaded`) to tell whether data fetching has finished.
+You'll notice we used `dataSource` from `this.state`. The next step is to add an empty `dataSource` to the object returned by `getInitialState`. Also, now that we're storing the data in `dataSource`, we should no longer use `this.state.movies` to avoid storing data twice. We can use boolean property of the state (`this.state.loaded`) to tell whether data fetching has finished.
 
 ```javascript
   getInitialState: function() {