Mention getId in navigate docs

Author: satya164

versioned_docs/version-5.x/navigation-actions.md

@@ -44,6 +44,9 @@ navigation.dispatch(
 );
 ```
 
+In a [stack navigator](stack-navigator.md), calling `navigate` with a screen name will result in different behavior based on if the screen is already present or not. If the screen is already present in the stack's history, it'll go back to that screen and remove any screens after that. If the screen is not present, it'll push a new screen.
+
+By default, the screen is identified by its name. But you can also customize it to take the params into account by using the [`getId`](screen.md#getid) prop.
 ### reset
 
 The `reset` action allows to reset the [navigation state](navigation-state.md) to the given state. It takes the following arguments:

versioned_docs/version-5.x/navigation-prop.md

@@ -78,6 +78,20 @@ function HomeScreen({ navigation: { navigate } }) {
 }
 ```
 
+In a [stack navigator](stack-navigator.md), calling `navigate` with a screen name will result in different behavior based on if the screen is already present or not. If the screen is already present in the stack's history, it'll go back to that screen and remove any screens after that. If the screen is not present, it'll push a new screen.
+
+For example, if you have a stack with the history `Home > Profile > Settings` and you call `navigate(Profile)`, the resulting screens will be `Home > Profile` as it goes back to `Profile` and removes the `Settings` screen.
+
+By default, the screen is identified by its name. But you can also customize it to take the params into account by using the [`getId`](screen.md#getid) prop.
+
+For example, say you have specified a `getId` prop for `Profile` screen:
+
+```js
+<Screen name={Profile} component={ProfileScreen} getId={({ params }) => params.userId} />
+```
+
+Now, if you have a stack with the history `Home > Profile (userId: bob) > Settings` and you call `navigate(Profile, { userId: 'alice' })`, the resulting screens will be `Home > Profile (userId: bob) > Settings > Profile (userId: alice)` since it'll add a new `Profile` screen as no matching screen was found.
+
 ### `goBack`
 
 The `goBack` method lets us go back to the previous screen in the navigator.

versioned_docs/version-5.x/screen.md

@@ -83,7 +83,7 @@ Callback to return an unique ID to use for the screen. It receives an object wit
 />
 ```
 
-When it's specified and doesn't return `undefined`, the unique ID is respected for any navigation. For a given screen name, there will always be only one screen corresponding to an ID.
+By default, calling `navigate('ScreenName', params)` identifies the screen by its name, and navigates to the existing screen instead of adding a new one. If you specify `getId` and it doesn't return `undefined`, the screen is identified by both the screen name and the returned ID.
 
 This is useful for preventing multiple instances of the same screen in the navigator, e.g. - when `params.userId` is used as an ID, subsequent navigation to the screen with the same `userId` will navigate to the existing screen instead of adding a new one to the stack. If the navigation was with a different `userId`, then it'll add a new screen.