Update OAuth2 Client to OAuth2 Resource Server

Fix section title to match the corresponding example

Signed-off-by: sach429 <satrajit.acharya@gmail.com>

docs/modules/ROOT/pages/servlet/oauth2/index.adoc

@@ -41,7 +41,7 @@ See xref:servlet/oauth2/resource-server/index.adoc[OAuth 2.0 Resource Server] fo
 To get started, add the `spring-security-oauth2-resource-server` dependency to your project.
 When using Spring Boot, add the following starter:
 
-.OAuth2 Client with Spring Boot
+.OAuth2 Resource Server with Spring Boot
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 Gradle::