use indent for displaying an escaped preprocessor conditional; add entry to CHANGELOG

CHANGELOG.adoc

@@ -18,6 +18,7 @@ Fixed::
 * Update xrefs to reflect module name change in asciidoctor component
 * Document the substitution values that the inline pass macro accepts; clarify the purpose of this macro (#37)
 * Move callouts for block image example to included line (#39)
+* Added missing leading backslash in example that shows how to escape an include directive in a verbatim block
 
 Added::
 * Import the AsciiDoc syntax quick reference content (#14)

modules/directives/pages/conditionals.adoc

@@ -29,10 +29,10 @@ The conditional preprocessor directives determine which lines to add and which o
 
 If you don't want a conditional preprocessor directive to be processed, you must escape it using a backslash.
 
-// the following listing uses attributes to avoid the backslash to be removed before rendering it in HTML
-[source,subs=attributes+]
+// NOTE: the following listing uses indentation to prevent the directive from being processed
+[source,indent=0]
 ----
-{backslash}ifdef::just-an-example[]
+ \ifdef::just-an-example[]
 ----
 
 Escaping the directive is necessary _even if it appears in a verbatim block_ since it's not aware of the surrounding document structure.