Update documentation of server.server-header for changes in 3009e514

See gh-4730

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/ServerProperties.java

@@ -131,7 +131,7 @@ public class ServerProperties
 	private Boolean useForwardHeaders;
 
 	/**
-	 * Value to use for the server header (uses servlet container default if empty).
+	 * Value to use for the Server response header (no header is sent if empty).
 	 */
 	private String serverHeader;
 

spring-boot-docs/src/main/asciidoc/appendix-application-properties.adoc

@@ -163,7 +163,7 @@ content into your application; rather pick only the properties that you need.
 	server.jsp-servlet.init-parameters.*= # Init parameters used to configure the JSP servlet
 	server.jsp-servlet.registered=true # Whether or not the JSP servlet is registered
 	server.port=8080 # Server HTTP port.
-	server.server-header= # The value sent in the server response header (uses servlet container default if empty)
+	server.server-header= # Value to use for the Server response header (no header is sent if empty)
 	server.servlet-path=/ # Path of the main dispatcher servlet.
 	server.use-forward-headers= # If X-Forwarded-* headers should be applied to the HttpRequest.
 	server.session.cookie.comment= # Comment for the session cookie.