Clarify expected jar size in getting started doc

Closes gh-34514

Author: snicoll

spring-boot-project/spring-boot-docs/src/docs/asciidoc/getting-started/first-application.adoc

@@ -283,7 +283,7 @@ Save your `pom.xml` and run `mvn package` from the command line, as follows:
 ----
 
 If you look in the `target` directory, you should see `myproject-0.0.1-SNAPSHOT.jar`.
-The file should be around 10 MB in size.
+The file should be around 18 MB in size.
 If you want to peek inside, you can use `jar tvf`, as follows:
 
 [source,shell,indent=0,subs="verbatim"]