Document isReady method

Author: satya164

versioned_docs/version-6.x/navigation-container.md

@@ -72,6 +72,12 @@ All of these methods will act as if they were called inside the currently focuse
 
 In addition to these methods, the ref object also includes the following special methods:
 
+#### `isReady`
+
+The `isReady` method returns a `boolean` indicating whether the navigation tree is ready. The navigation tree is ready when the `NavigationContainer` contains at least one navigator and all of the navigators have finished mounting.
+
+This can be used to determine whether it's safe to dispatch navigation actions without getting an error. See [handling initialization](navigating-without-navigation-prop.md#handling-initialization) for more details.
+
 #### `resetRoot`
 
 The `resetRoot` method lets you reset the state of the navigation tree to the specified state object:

versioned_docs/version-7.x/navigation-container.md

@@ -73,6 +73,12 @@ All of these methods will act as if they were called inside the currently focuse
 
 In addition to these methods, the ref object also includes the following special methods:
 
+#### `isReady`
+
+The `isReady` method returns a `boolean` indicating whether the navigation tree is ready. The navigation tree is ready when the `NavigationContainer` contains at least one navigator and all of the navigators have finished mounting.
+
+This can be used to determine whether it's safe to dispatch navigation actions without getting an error. See [handling initialization](navigating-without-navigation-prop.md#handling-initialization) for more details.
+
 #### `resetRoot`
 
 The `resetRoot` method lets you reset the state of the navigation tree to the specified state object:
@@ -214,6 +220,10 @@ Example:
 </NavigationContainer>
 ```
 
+This callback won't fire if there are no navigators rendered inside the container.
+
+The current status can be obtained with the [`isReady`](#isready) method on the ref.
+
 ### `onUnhandledAction`
 
 Function which is called when a navigation action is not handled by any of the navigators.