Fix JVM heap size docs for 5.0

Closes #20587

docs/reference/setup/sysconfig/heap_size.asciidoc

@@ -1,8 +1,8 @@
 [[heap-size]]
 === Set JVM heap size via jvm.options
 
-In development mode, Elasticsearch tells the JVM to use a heap with a minimum
-size of 256 MB and a maximum size of 1 GB. When moving to production, it is
+By default, Elasticsearch tells the JVM to use a heap with a minimum
+and maximum size of 2 GB. When moving to production, it is
 important to configure heap size to ensure that Elasticsearch has enough
 heap available.
 
@@ -48,8 +48,8 @@ Here are examples of how to set the heap size via the jvm.options file:
 
 [source,txt]
 ------------------
-Xms2g <1>
-Xmx2g <2>
+-Xms2g <1>
+-Xmx2g <2>
 ------------------
 <1> Set the minimum heap size to 2g.
 <2> Set the maximum heap size to 2g.