Revised SimpleEvaluationContext example

Issue: SPR-17581

Author: jhoeller

src/asciidoc/core-expressions.adoc

@@ -232,11 +232,10 @@ being placed in it. A simple example:
 	Simple simple = new Simple();
 	simple.booleanList.add(true);
 
-	SimpleEvaluationContext context = SimpleEvaluationContext().create();
-
-	// false is passed in here as a string. SpEL and the conversion service will
-	// correctly recognize that it needs to be a Boolean and convert it
+	EvaluationContext context = SimpleEvaluationContext.forReadOnlyDataBinding().build();
 
+	// "false" is passed in here as a String. SpEL and the conversion service
+	// will recognize that it needs to be a Boolean and convert it accordingly.
 	parser.parseExpression("booleanList[0]").setValue(context, simple, "false");
 
 	// b will be false