Fix property name in "Task Execution and Scheduling" example

See gh-18331

Author: polarbear567

spring-boot-project/spring-boot-docs/src/main/asciidoc/spring-boot-features.adoc

@@ -5411,7 +5411,7 @@ Those default settings can be fine-tuned using the `spring.task.execution` names
 
 [source,properties,indent=0]
 ----
-	spring.task.execution.pool.max-threads=16
+	spring.task.execution.pool.max-size=16
 	spring.task.execution.pool.queue-capacity=100
 	spring.task.execution.pool.keep-alive=10s
 ----