Add manually enableCrashlyticsCollection docs (#149)

Pull request invertase/react-native-firebase#1718

docs/_sidebar.yaml

@@ -223,6 +223,8 @@
     - to: "/android"
       text: Install on Android
       icon: android
+    - to: "/manual-initialization"
+      text: Manual Initialization
     - type: divider
     - type: reference
       files:

docs/crashlytics/manual-initialization.md

@@ -0,0 +1,32 @@
+# Manual Initialization
+
+By default, Firebase Crashlytics automatically collects crash reports for all your app's users. To give users more control over the data they send, you can enable opt-in reporting instead.
+
+To do that, you have to disable automatic collection and initialize Crashlytics only for opt-in users.
+
+## 1) Disable automatic initialization
+
+### iOS:
+
+Turn off automatic collection with a new key to your `Info.plist` file:
+
+* Key: `firebase_crashlytics_collection_enabled`
+* Value: `false`
+
+### Android:
+
+Turn off automatic collection with a meta-data tag in your `AndroidManifest.xml` file:
+
+```xml
+<meta-data
+    android:name="firebase_crashlytics_collection_enabled"
+    android:value="false" />
+```
+
+## 2) Enable collection at runtime
+
+Initializing Crashlytics in your js code:
+
+```js
+firebase.crashlytics().enableCrashlyticsCollection();
+```

docs/crashlytics/reference/crashlytics.md

@@ -84,3 +84,8 @@ Set the user ID to show alongside any subsequent crash reports.
 | Parameter |     |
 | --------- | --- |
 | userId    | **string** <br /> The user's ID. |
+
+### enableCrashlyticsCollection
+[method]enableCrashlyticsCollection() returns void;[/method]
+
+Enable Crashlytics reporting. Only avaliable when [disabled automatic initialization](../manual-initialization).