Fix appendix

Remove extraneous `////` left over from a previously commented out block.

Author: garyrussell

src/reference/asciidoc/appendix.adoc

@@ -75,8 +75,6 @@ dependencies {
 
 The test scope dependencies are only needed if you are using the embedded Kafka broker in tests.
 
-////
-
 [appendix]
 [[history]]
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