Merge pull request #6036 from segmentio/niall/rn_anon_identify

Add anonymous identify method info

Author: rchinn1

src/connections/sources/catalog/libraries/mobile/react-native/implementation.md

@@ -14,6 +14,8 @@ Once you've installed the Analytics React Native library, you can start collecti
 
 The [Identify](/docs/connections/spec/identify/) method lets you tie a user to their actions and record traits about them. This includes a unique user ID and any optional traits you know about them like their email, name, or address. The traits option can include any information you want to tie to the user. When using any of the [reserved user traits](/docs/connections/spec/identify/#traits), be sure the information reflects the name of the trait. For example, `email` should always be a string of the user's email address.
 
+To send updates for anonymous users who haven't yet signed up for your app, pass `null` for the `userId` like in the example below. 
+
 {% codeexample %}
 {% codeexampletab Method signature %}
 ```js
@@ -30,6 +32,13 @@ identify('user-123', {
   email: '[email protected]',
   plan: 'premium',
 });
+
+//To send traits for an anonymous user
+identify(null, {
+  username: 'MisterWhiskers',
+  email: '[email protected]',
+  plan: 'premium',
+});
 ```
 {% endcodeexampletab %}
 {% endcodeexample %}