Add portion to grab the anonymousId with npm library

Author: bcaudillo

src/connections/sources/catalog/libraries/website/javascript/identity.md

@@ -45,6 +45,11 @@ analytics.user().anonymousId();
 
 If the user's `anonymousId` is `null` (meaning not set) when you call this function, Analytics.js automatically generated and sets a new `anonymousId` for the user.
 
+Using the npm library you'll need to grab the user's current `anonymousId` with the following: 
+
+```js
+analytics.instance?.user().anonymousId()
+```
 
 ### Refreshing the Anonymous ID