Minor fix

These four items, not three items, constitute the auth process:

. A user is prompted to log in with a username and password.
. The system (successfully) verifies that the password is correct for the username.
. The context information for that user is obtained (their list of roles and so on).
. A security context is established for the user

Author: behrangsa

docs/manual/src/docs/asciidoc/_includes/servlet/architecture/technical-overview.adoc

@@ -156,7 +156,7 @@ Let's consider a standard authentication scenario that everyone is familiar with
 . The user proceeds, potentially to perform some operation which is potentially protected by an access control mechanism which checks the required permissions for the operation against the current security context information.
 
 
-The first three items constitute the authentication process so we'll take a look at how these take place within Spring Security.
+The first four items constitute the authentication process so we'll take a look at how these take place within Spring Security.
 
 . The username and password are obtained and combined into an instance of `UsernamePasswordAuthenticationToken` (an instance of the `Authentication` interface, which we saw earlier).
 . The token is passed to an instance of `AuthenticationManager` for validation.