Ensure documentation has consistent relative links

Summary:
Explain the **motivation** for making this change. What existing problem does the pull request solve?

I had tried fixing a broken link in a previous commit (facebook#11453). My commit was merged, but it did not resolve the underlying problem. I have looked into how links should be formed for the docs and have fixed the original problem as well as updated all other links to be consistent.

Previous link formats:

- /docs/sample.html <-- broken link
- sample.html <-- broken link
- https://facebook.github.io/react-native/docs/sample.html <-- works
- /react-native/docs/sample.html <-- works
- docs/sample.html <-- works (permalink format)

This PR updates all links to the permalink format.

**Test plan (required)**
I ran the website locally and manually tested half of the links in each category. They all worked.
```
$ cd website
$ npm install && npm start
```
Closes facebook#12064

Differential Revision: D4489153

Pulled By: mkonicek

fbshipit-source-id: bf0231d941ba147317595c3b3466dc579a887169

Author: PaulMest

Libraries/Alert/AlertIOS.js

@@ -100,7 +100,7 @@ type ButtonsArray = Array<{
  * );
  * ```
  *
- * We recommend using the [`Alert.alert`](alert.html) method for
+ * We recommend using the [`Alert.alert`](docs/alert.html) method for
  * cross-platform support if you don't need to create iOS-only prompts.
  *
  */

Libraries/CameraRoll/CameraRoll.js

@@ -111,7 +111,7 @@ var getPhotosReturnChecker = createStrictShapeTypeChecker({
 /**
  * `CameraRoll` provides access to the local camera roll / gallery.
  * Before using this you must link the `RCTCameraRoll` library.
- * You can refer to [Linking](https://facebook.github.io/react-native/docs/linking-libraries-ios.html) for help.
+ * You can refer to [Linking](docs/linking-libraries-ios.html) for help.
  *
  * ### Permissions
  * The user's permission is required in order to access the Camera Roll on devices running iOS 10 or later.

Libraries/Components/Button.js

@@ -29,8 +29,8 @@ const invariant = require('fbjs/lib/invariant');
  * <center><img src="img/buttonExample.png"></img></center>
  *
  * If this button doesn't look right for your app, you can build your own
- * button using [TouchableOpacity](https://facebook.github.io/react-native/docs/touchableopacity.html)
- * or [TouchableNativeFeedback](https://facebook.github.io/react-native/docs/touchablenativefeedback.html).
+ * button using [TouchableOpacity](docs/touchableopacity.html)
+ * or [TouchableNativeFeedback](docs/touchablenativefeedback.html).
  * For inspiration, look at the [source code for this button component](https://github.com/facebook/react-native/blob/master/Libraries/Components/Button.js).
  * Or, take a look at the [wide variety of button components built by the community](https://js.coach/react-native?search=button).
  *

Libraries/Components/Navigation/NavigatorIOS.ios.js

@@ -133,7 +133,7 @@ type Event = Object;
  * animations and behavior from UIKIt.
  *
  * As the name implies, it is only available on iOS. Take a look at
- * [`Navigator`](/react-native/docs/navigator.html) for a similar solution for your
+ * [`Navigator`](docs/navigator.html) for a similar solution for your
  * cross-platform needs, or check out
  * [react-native-navigation](https://github.com/wix/react-native-navigation), a
  * component that aims to provide native navigation on both iOS and Android.

Libraries/Components/TextInput/TextInput.js

@@ -482,7 +482,7 @@ const TextInput = React.createClass({
      * see [Issue#7070](https://github.com/facebook/react-native/issues/7070)
      * for more detail.
      *
-     * [Styles](/react-native/docs/style.html)
+     * [Styles](docs/style.html)
      */
     style: Text.propTypes.style,
     /**

Libraries/Components/View/View.js

@@ -76,9 +76,9 @@ const statics = {
 
 /**
  * The most fundamental component for building a UI, `View` is a container that supports layout with
- * [flexbox](/react-native/docs/flexbox.html), [style](/react-native/docs/style.html),
- * [some touch handling](/react-native/docs/handling-touches.html), and
- * [accessibility](/react-native/docs/accessibility.html) controls. `View` maps directly to the
+ * [flexbox](docs/flexbox.html), [style](docs/style.html),
+ * [some touch handling](docs/handling-touches.html), and
+ * [accessibility](docs/accessibility.html) controls. `View` maps directly to the
  * native view equivalent on whatever platform React Native is running on, whether that is a
  * `UIView`, `<div>`, `android.view`, etc.
  *
@@ -101,7 +101,7 @@ const statics = {
  * }
  * ```
  *
- * > `View`s are designed to be used with [`StyleSheet`](/react-native/docs/style.html) for clarity
+ * > `View`s are designed to be used with [`StyleSheet`](docs/style.html) for clarity
  * > and performance, although inline styles are also supported.
  *
  * ### Synthetic Touch Events
@@ -243,7 +243,7 @@ const View = React.createClass({
      * - `'allowsDirectInteraction'` - The element allows direct touch interaction for VoiceOver users.
      * - `'pageTurn'` - Informs VoiceOver that it should scroll to the next page when it finishes reading the contents of the element.
      *
-     * See the [Accessibility guide](/react-native/docs/accessibility.html#accessibilitytraits-ios)
+     * See the [Accessibility guide](docs/accessibility.html#accessibilitytraits-ios)
      * for more information.
      *
      * @platform ios

Libraries/CustomComponents/Navigator/Navigator.js

@@ -289,7 +289,7 @@ var GESTURE_ACTIONS = [
  * ```
  * In the above example, the newly pushed scene will float up from the bottom.
  * See `Navigator.SceneConfigs` for default animations and more info on
- * available [scene config options](/react-native/docs/navigator.html#configurescene).
+ * available [scene config options](docs/navigator.html#configurescene).
  */
 var Navigator = React.createClass({
 

Libraries/Text/Text.js

@@ -185,7 +185,7 @@ const Text = React.createClass({
      * for a `Text` element is `true`.
      *
      * See the
-     * [Accessibility guide](/react-native/docs/accessibility.html#accessible-ios-android)
+     * [Accessibility guide](docs/accessibility.html#accessible-ios-android)
      * for more information.
      */
     accessible: PropTypes.bool,

docs/AndroidBuildingFromSource.md

@@ -144,7 +144,7 @@ gradle.projectsLoaded {
 
 ## Testing
 
-If you made changes to React Native and submit a pull request, all tests will run on your pull request automatically. To run the tests locally, see [Testing](/react-native/docs/testing.html).
+If you made changes to React Native and submit a pull request, all tests will run on your pull request automatically. To run the tests locally, see [Testing](docs/testing.html).
 
 ## Troubleshooting
 

docs/GettingStarted.md

@@ -10,7 +10,7 @@ next: tutorial
 Welcome to React Native! This page will help you install React Native on
 your system, so that you can build apps with it right away. If you already
 have React Native installed, you can skip ahead to the
-[Tutorial](/react-native/docs/tutorial.html).
+[Tutorial](docs/tutorial.html).
 
 The instructions are a bit different depending on your development operating system, and whether you want to start developing for iOS or Android. If you
 want to develop for both iOS and Android, that's fine - you just have to pick