Remove NOTE bookmarks

Originally, there were two references to "[[NOTE]]" which was
confusing since Asciidoc can't have two bookmarks of the same name.

Changed these to "[NOTE]" so they would display the "note" component
in the docs.

Issue: gh-5866

docs/manual/src/docs/asciidoc/_includes/reactive/oauth2/resource-server.adoc

@@ -4,7 +4,7 @@
 Spring Security provides OAuth2 Resource Server support with JWT tokens.
 
 
-[[NOTE]]
+[NOTE]
 ====
 A complete working example can be found in {gh-samples-url}/boot/oauth2resourceserver-webflux[*OAuth 2.0 Resource Server WebFlux sample*].
 ====

docs/manual/src/docs/asciidoc/_includes/reactive/registered-oauth2-authorized-client.adoc

@@ -3,7 +3,7 @@
 
 Spring Security allows resolving an access token using `@RegisteredOAuth2AuthorizedClient`.
 
-[[NOTE]]
+[NOTE]
 ====
 A working example can be found in {gh-samples-url}/boot/oauth2webclient-webflux[*OAuth 2.0 WebClient WebFlux sample*].
 ====