Update headers.md

Author: vonovak

docs/headers.md

@@ -34,7 +34,7 @@ class DetailsScreen extends React.Component {
 
 ## Using params in the title
 
-In order to use params in the title, we need to make `navigationOptions` a function that returns a configuration object. It might be tempting to try to use `this.props` inside of `navigationOptions`, but because it is a static property of the component, `this` does not refer to an instance of the component and therefore no props are available. Instead, if we make `navigationOptions` a function then React Navigation will call it with an object containing `{ navigation, navigationOptions, screenProps }` -- in this case, all we care about is `navigation`, which is the same object that is passed to your screen props as `this.props.navigation`. You may recall that we can get the params from `navigation` through `navigation.state.params`, and so we do this below to extract a param and use it as a title.
+In order to use params in the title, we need to make `navigationOptions` a function that returns a configuration object. It might be tempting to try to use `this.props` inside of `navigationOptions`, but because it is a static property of the component, `this` does not refer to an instance of the component and therefore no props are available. Instead, if we make `navigationOptions` a function then React Navigation will call it with an object containing `{ navigation, navigationOptions, screenProps }` -- in this case, all we care about is `navigation`, which is the same object that is passed to your screen props as `this.props.navigation`. You may recall that we can get the params from `navigation` through `navigation.getParam` or `navigation.state.params`, and so we do this below to extract a param and use it as a title.
 
 ```js
 class DetailsScreen extends React.Component {
@@ -100,7 +100,7 @@ class HomeScreen extends React.Component {
 <a href="https://snack.expo.io/@react-navigation/setting-header-styles-v2" target="blank" class="run-code-button">&rarr; Run this code</a>
 
 There are a couple of things to notice here:
-1. On iOS the status bar text and icons are black, and this doesn't look great over a dark colored background. We won't discuss it here, but you should be sure to configure the status bar to fit with your screen colors [as described in the status bar guide](status-bar.html).
+1. On iOS, the status bar text and icons are black, and this doesn't look great over a dark-colored background. We won't discuss it here, but you should be sure to configure the status bar to fit with your screen colors [as described in the status bar guide](status-bar.html).
 2. The configuration we set only applies to the home screen; when we navigate to the details screen, the default styles are back. We'll look at how to share `navigationOptions` between screens now.
 
 ## Sharing common `navigationOptions` across screens