chore: update doc

update doc

packages/authentication/docs/authentication-system.md

@@ -167,20 +167,20 @@ And the abstractions for:
 ## Registering an authentication strategy via an extension point
 
 Authentication strategies register themselves to an authentication strategy
-resolver using an
+provider using an
 [ExtensionPoint/Extension Pattern](https://wiki.eclipse.org/FAQ_What_are_extensions_and_extension_points%3F)
 as described in the
 [Greeter extension example](https://github.com/strongloop/loopback-next/tree/master/examples/greeter-extension).
 
 The `AuthenticationStrategyProvider` class in
-`src/providers/auth-strategy.provider.ts` declares an `extension point` named
+`src/providers/auth-strategy.provider.ts` (shown below) declares an `extension point` named
 `AuthenticationBindings.AUTHENTICATION_STRATEGY_EXTENSION_POINT_NAME` via the
-`@extensionPoint` decorator. `AuthenticationStrategyProvider` is responsible for
-returning an authentication strategy which has a specific **name** and has been
-registered as an **extension** of the aforementioned **extension point** with
-the aid of the `@extensions()` decorator. The binding scope is set to
-**transient** because an authentication strategy **may** differ with each
-request.
+`@extensionPoint` decorator. The binding scope is set to **transient** because
+an authentication strategy **may** differ with each request.
+`AuthenticationStrategyProvider` is responsible for finding (with the aid of the
+`@extensions()` **getter** decorator) and returning an authentication strategy
+which has a specific **name** and has been registered as an **extension** of the
+aforementioned **extension point**.
 
 ```ts
 @extensionPoint(
@@ -265,10 +265,10 @@ export class BasicAuthenticationStrategy implements AuthenticationStrategy {
   }
 ```
 
-A custom sequence must be created to insert `AuthenticationBindings.AUTH_ACTION`
-action. The `AuthenticateFn` function interface is implemented by the `value()`
-function of `AuthenticateActionProvider` class in
-`src/providers/authentication.provider.ts`. **( New name TBD)**
+A custom sequence must be created to insert the
+`AuthenticationBindings.AUTH_ACTION` action. The `AuthenticateFn` function
+interface is implemented by the `value()` function of
+`AuthenticateActionProvider` class in `/src/providers/auth-action.provider.ts`.
 
 ```ts
 class SequenceIncludingAuthentication implements SequenceHandler {
@@ -327,7 +327,7 @@ class SequenceIncludingAuthentication implements SequenceHandler {
 ```
 
 Then custom sequence must be bound to the application, and the authentication
-strategy must be added as an extension of the extension point using the
+strategy must be added as an **extension** of the **extension point** using the
 `addExtension` function.
 
 ```ts