Fix inconsistency in Graceful Shutdown section

See gh-46917
Closes gh-48284

documentation/spring-boot-docs/src/docs/antora/modules/reference/pages/web/graceful-shutdown.adoc

@@ -1,7 +1,7 @@
 [[web.graceful-shutdown]]
 = Graceful Shutdown
 
-Graceful shutdown is enabled by default with all four embedded web servers (Jetty, Reactor Netty, and Tomcat) and with both reactive and servlet-based web applications.
+Graceful shutdown is enabled by default with all three embedded web servers (Jetty, Reactor Netty, and Tomcat) and with both reactive and servlet-based web applications.
 It occurs as part of closing the application context and is performed in the earliest phase of stopping javadoc:org.springframework.context.SmartLifecycle[] beans.
 This stop processing uses a timeout which provides a grace period during which existing requests will be allowed to complete but no new requests will be permitted.