docs(provider): Explain how to get access to LinkedIn authentication (#…

…1706)

www/docs/providers/linkedin.md

@@ -11,6 +11,10 @@ https://docs.microsoft.com/en-us/linkedin/shared/authentication/authorization-co
 
 https://www.linkedin.com/developers/apps/
 
+From the Auth tab get the client ID and client secret. On the same tab, add redirect URLs such as http://localhost:3000/api/auth/callback/linkedin so LinkedIn can correctly redirect back to your application. Finally, head over to the Products tab and enable the "Sign In with LinkedIn" product. The LinkedIn team will review and approve your request before you can test it out.
+
+![image](https://user-images.githubusercontent.com/330396/114429603-68195600-9b72-11eb-8311-62e58383c42b.png)
+
 ## Example
 
 ```js