Polish Username Password Storage wording

Issue gh-7801

docs/manual/src/docs/asciidoc/_includes/servlet/authentication/unpwd/storage/index.adoc

@@ -1,8 +1,8 @@
 [[servlet-authentication-unpwd-storage]]
 = User Storage
 
-Spring Security's <<servlet-authentication-userdetailsservice,`UserDetailsService`>> allows for storing user information when authenticating with a username/password.
-`UserDetailsService` is used by Spring Security when it is configured to <<servlet-authentication-unpwd-input,accept a username/password>> for authentication.
+Spring Security's <<servlet-authentication-userdetailsservice,`UserDetailsService`>> allows for storing user information when authenticating by comparing a username password.
+A configured `UserDetailsService` is used by Spring Security when it is configured to <<servlet-authentication-unpwd-input,accept a username/password>> for authentication.
 
 // FIXME: Once it is retrieved it is validated using DaoAuthenticationProvider