Remove a bad callout from the new debugging docs

It was a leftover and doesn't break the usual build but breaks the docs
build.

docs/reference/modules/scripting/painless-debugging.asciidoc

@@ -88,8 +88,6 @@ The response looks like:
 // TESTRESPONSE[s/\.\.\./"script_stack": $body.error.caused_by.script_stack, "script": $body.error.caused_by.script, "lang": $body.error.caused_by.lang, "caused_by": $body.error.caused_by.caused_by, "reason": $body.error.caused_by.reason/]
 // TESTRESPONSE[s/"to_string": ".+"/"to_string": $body.error.caused_by.to_string/]
 
-<1> This is the explanation.
-
 // TODO we should build some javadoc like mashup so people don't have to jump through these hoops.
 
 Once you have the class of an object you can go