Update authentication.md

Removed duplicate instruction to inject a service which was listed in the previous section: "Don't forget to inject the JwtService provider into the `AuthService`."

Author: kunalrgarg

content/security/authentication.md

@@ -272,7 +272,7 @@ export class AuthService {
 }
 ```
 
-We're using the `@nestjs/jwt` library, which supplies a `signAsync()` function to generate our JWT from a subset of the `user` object properties, which we then return as a simple object with a single `access_token` property. Note: we choose a property name of `sub` to hold our `userId` value to be consistent with JWT standards. Don't forget to inject the JwtService provider into the `AuthService`.
+We're using the `@nestjs/jwt` library, which supplies a `signAsync()` function to generate our JWT from a subset of the `user` object properties, which we then return as a simple object with a single `access_token` property. Note: we choose a property name of `sub` to hold our `userId` value to be consistent with JWT standards.
 
 We now need to update the `AuthModule` to import the new dependencies and configure the `JwtModule`.