Update redirect-uri-template in oauth sample and docs

Fixes gh-11014

spring-boot-samples/spring-boot-sample-oauth2-client/README.adoc

@@ -2,7 +2,7 @@
 
 == Register Github OAuth2 application
 To run the sample, you need to link:https://github.com/settings/applications/new[register an OAuth application on Github].
-While registering your application, ensure the Authorization callback URL is set to http://localhost:8080/oauth2/authorize/code/github.
+While registering your application, ensure the Authorization callback URL is set to http://localhost:8080/login/oauth2/code/github.
 After completing the registration, you will have a new OAuth Application with a Client ID and Client Secret.
 
 == Configuring application.yml

spring-boot-samples/spring-boot-sample-oauth2-client/src/main/resources/application.yml

@@ -9,11 +9,11 @@ spring:
             client-name: Github user
             provider: github
             scope: user
-            redirect_uri: http://localhost:8080/oauth2/authorize/code/github
+            redirect-uri-template: http://localhost:8080/login/oauth2/code/github
           github-client-2:
             client-id: ${APP-CLIENT-ID}
             client-secret: ${APP-CLIENT-SECRET}
             client-name: Github email
             provider: github
             scope: user:email
-            redirect_uri: http://localhost:8080/oauth2/authorize/code/github
+            redirect-uri-template: http://localhost:8080/login/oauth2/code/github