application.yml fix in "Single Sign On With GitHub" chapter

Author: csfulop

simple/README.adoc

@@ -122,13 +122,14 @@ Then, to make the link to GitHub, add the following to your `application.yml`:
 .application.yml
 [source,yaml]
 ----
-security:
-  oauth2:
-    client:
-      registration:
-        github:
-          clientId: github-client-id
-          clientSecret: github-client-secret
+spring:
+  security:
+    oauth2:
+	  client:
+	    registration:
+		  github:
+		    clientId: github-client-id
+		    clientSecret: github-client-secret
 # ...
 ----