Fix an instance of unnecessarily gendered language

The gender of the user doesn't matter.

Author: jamiecobbett

views/md/introduction.md

@@ -93,7 +93,7 @@ If you want to play with JWT and put these concepts into practice, you can use [
 ![JWT.IO Debugger](https://cdn.auth0.com/blog/legacy-app-auth/legacy-app-auth-5.png)
 
 ## How do JSON Web Tokens work?
-In authentication, when the user successfully logs in using his credentials, a JSON Web Token will be returned and must be saved locally (typically in local storage, but cookies can be also used), instead of the traditional approach of creating a session in the server and returning a cookie.
+In authentication, when the user successfully logs in using their credentials, a JSON Web Token will be returned and must be saved locally (typically in local storage, but cookies can be also used), instead of the traditional approach of creating a session in the server and returning a cookie.
 
 Whenever the user wants to access a protected route or resource, the user agent should send the JWT, typically in the **Authorization** header using the **Bearer** schema. The content of the header should look like the following: